Email alert
RSS2015 Vol. 27, No. 10
Recommend Articles
Display Method:
2015,
27: 103201.
doi: 10.11884/HPLPB201527.103201
Abstract:
With the enlightenment from the common knowledge about electromagnetic environmental effects(E3) test and evaluation(TE), the concepts of complex radiation environments and military system radiation environments effects TE are proposed. The decomposable radiation environments are discussed of acoustic radiation and electromagnetic radiation across the spectrum including radiowaves, microwaves, terahertz radiation, infrared light, visible light, and gamma ray. All natural and man-made radiation environments profiles are formulated as M, N,O and G. Then, from the point of electronic warfare, the complexity r of the radiation environments is defined with the help of similarity principle. Finally, based on the statistical independence of the radiation environments profiles, the military system complex radiation environments effects TE methods are given.
With the enlightenment from the common knowledge about electromagnetic environmental effects(E3) test and evaluation(TE), the concepts of complex radiation environments and military system radiation environments effects TE are proposed. The decomposable radiation environments are discussed of acoustic radiation and electromagnetic radiation across the spectrum including radiowaves, microwaves, terahertz radiation, infrared light, visible light, and gamma ray. All natural and man-made radiation environments profiles are formulated as M, N,O and G. Then, from the point of electronic warfare, the complexity r of the radiation environments is defined with the help of similarity principle. Finally, based on the statistical independence of the radiation environments profiles, the military system complex radiation environments effects TE methods are given.
2015,
27: 103202.
doi: 10.11884/HPLPB201527.103202
Abstract:
The feasibility of the reverberation chamber using frequency stirring was analysed in theory. The field uniformity and statistical characteristics within the reverberation chamber were simulated and tested. And the application to measuring shielding effectiveness was investigated. The results show that the field uniformity could be got by frequency stirring, the electric field right angle components obeyed Rayleigh distribution, and the field uniformity and statistical characteristics became better with the frequency rising. The shielding effectiveness of small enclousres with an aperture was tested in a frequency stirring reverberation chamber, and the SE was about 15 dB, which was fit with the test results of the mechanical stirring reverberation chamber.
The feasibility of the reverberation chamber using frequency stirring was analysed in theory. The field uniformity and statistical characteristics within the reverberation chamber were simulated and tested. And the application to measuring shielding effectiveness was investigated. The results show that the field uniformity could be got by frequency stirring, the electric field right angle components obeyed Rayleigh distribution, and the field uniformity and statistical characteristics became better with the frequency rising. The shielding effectiveness of small enclousres with an aperture was tested in a frequency stirring reverberation chamber, and the SE was about 15 dB, which was fit with the test results of the mechanical stirring reverberation chamber.
M-type barium ferrite ceramic microsphere core-shell-hollow structure microwave absorption materials
2015,
27: 103203.
doi: 10.11884/HPLPB201527.103203
Abstract:
The M-type barium ferrite hollow ceramic microsphere microwave absorption materials were prepared with self-reactive quenching method. The Ni-Co composite layers were plated on the surface of the materials by using ultrasonic chemical electroless plating method. The materials had the core-shell-hollow structure. From the SEM, EDS and XRD analyzsis, the results show that the materials have middle hollow structure and its phase BaFe12O19 is M-type barium ferrite. The surface of the materials was plated with Ni-Co composite layers by using chemical electroless plating. From the test of microwave absorption property, after chemical electroless plating its microwave absorption properties were raised. The lowest reflection rate was -28.62 dB and the band width less than -10 dB was 3.33 GHz in the frequency range of 2-18 GHz when the thickness was 2.10 mm.
The M-type barium ferrite hollow ceramic microsphere microwave absorption materials were prepared with self-reactive quenching method. The Ni-Co composite layers were plated on the surface of the materials by using ultrasonic chemical electroless plating method. The materials had the core-shell-hollow structure. From the SEM, EDS and XRD analyzsis, the results show that the materials have middle hollow structure and its phase BaFe12O19 is M-type barium ferrite. The surface of the materials was plated with Ni-Co composite layers by using chemical electroless plating. From the test of microwave absorption property, after chemical electroless plating its microwave absorption properties were raised. The lowest reflection rate was -28.62 dB and the band width less than -10 dB was 3.33 GHz in the frequency range of 2-18 GHz when the thickness was 2.10 mm.
2015,
27: 103204.
doi: 10.11884/HPLPB201527.103204
Abstract:
As a result of interaction between the spacecraft and the charged particles in plasma environment，the surface charging inevitability occurs. On the back grounded dielectric material，there exists a potential difference between the upper surface and the grounded back surface. The surface potential plays an important role in charging and discharging effects. Discharging occurs if the generated electric fields exceed the breakdown threshold. Taking a comprehensive consideration of the plasma particles mass，temperature and density，the secondary electron effects of the dielectric materials，body leakage current and the flight speed，a general expression for surface potential of back grounded dielectric material in plasma environment is derived using the formula of particles Maxwellian velocity distribution. Consequently，the dependences of the surface potential on each of the parameters are discussed concerning the geosynchronous orbit (GEO) environment，and some useful rules are summarized for the surface charging of back grounded dielectric material immersed in plasma. The method introduced here can facilitate the risk assessment for spacecraft surface charging and provide certain theoretical basis for spacecraft charging protection.
As a result of interaction between the spacecraft and the charged particles in plasma environment，the surface charging inevitability occurs. On the back grounded dielectric material，there exists a potential difference between the upper surface and the grounded back surface. The surface potential plays an important role in charging and discharging effects. Discharging occurs if the generated electric fields exceed the breakdown threshold. Taking a comprehensive consideration of the plasma particles mass，temperature and density，the secondary electron effects of the dielectric materials，body leakage current and the flight speed，a general expression for surface potential of back grounded dielectric material in plasma environment is derived using the formula of particles Maxwellian velocity distribution. Consequently，the dependences of the surface potential on each of the parameters are discussed concerning the geosynchronous orbit (GEO) environment，and some useful rules are summarized for the surface charging of back grounded dielectric material immersed in plasma. The method introduced here can facilitate the risk assessment for spacecraft surface charging and provide certain theoretical basis for spacecraft charging protection.
2015,
27: 103205.
doi: 10.11884/HPLPB201527.103205
Abstract:
The laser can do great damage to optical elements, which has become a problem for developing high power and high energy lasers. A main cause of the damage is the highly absorption of laser by impurities imbedded in optical material. The T-matrix method is adopted for simulating the effects of titanium impurities in silicon on the electric-field distribution of laser. We discuss the effects of some parameters, such as the number of impurities, the radius of the impurity, the distance of impurities, the configuration of impurities and the relative dielectric constant of impurity. With the simulation, we know that the maximum of electric-field magnitude lies in the polarization direction of incident wave, the increase of electric-field magnitude depends on the coupling of two adjacent impurities, the maximum of electric-field magnitude becomes larger with reducing the distance of two impurities, and the maximum of electric-field magnitude can be enlarged with reducing the real part or increasing the imaginary part of relative dielectric constant.
The laser can do great damage to optical elements, which has become a problem for developing high power and high energy lasers. A main cause of the damage is the highly absorption of laser by impurities imbedded in optical material. The T-matrix method is adopted for simulating the effects of titanium impurities in silicon on the electric-field distribution of laser. We discuss the effects of some parameters, such as the number of impurities, the radius of the impurity, the distance of impurities, the configuration of impurities and the relative dielectric constant of impurity. With the simulation, we know that the maximum of electric-field magnitude lies in the polarization direction of incident wave, the increase of electric-field magnitude depends on the coupling of two adjacent impurities, the maximum of electric-field magnitude becomes larger with reducing the distance of two impurities, and the maximum of electric-field magnitude can be enlarged with reducing the real part or increasing the imaginary part of relative dielectric constant.
2015,
27: 103206.
doi: 10.11884/HPLPB201527.103206
Abstract:
Spectral and directional control of infrared radiation based on excitation of confined electromagnetic resonant modes opens up a viable way for design and study of new semiconductor materials, electromagnetic and thermal analysis of micro/nano scale electronics. In this paper, we present numerical simulation results of the thermal radiative properties of a silicon carbide (SiC) thermal emitter/absorber. We illustrate different electromagnetic resonant modes which can be excited with the structure and the process of radiation spectrum optimization based on a non-linear optimization algorithm. The results show that the spectral and directional control of thermal emission/absorption can be efficiently achieved by adjusting the geometrical parameters of the structure.
Spectral and directional control of infrared radiation based on excitation of confined electromagnetic resonant modes opens up a viable way for design and study of new semiconductor materials, electromagnetic and thermal analysis of micro/nano scale electronics. In this paper, we present numerical simulation results of the thermal radiative properties of a silicon carbide (SiC) thermal emitter/absorber. We illustrate different electromagnetic resonant modes which can be excited with the structure and the process of radiation spectrum optimization based on a non-linear optimization algorithm. The results show that the spectral and directional control of thermal emission/absorption can be efficiently achieved by adjusting the geometrical parameters of the structure.
2015,
27: 103207.
doi: 10.11884/HPLPB201527.103207
Abstract:
The metamaterial exhibits more and more novel electromagnetic characteristics, such as the electromagnetic cloak, the frequency selective surface, the energy selective surface, and the like. The metamaterial is widely applied to antenna design, electromagnetic protection and other engineering zones. In this paper, the research on the electromagnetic characteristics of mue near zero (MNZ) material is completed by theoretical analysis and numerical simulation method. Considering a two-dimension MNZ structure, the impedance match between MNZ material and air and the continuity of propagation constant is theoretically analyzed, and it is verified with numerical simulation. It turns out that such characteristic can result in forming plane wave. Also, it is found that a good impedance match can be achieved if the electromagnetic wave parallels to the boundary of MNZ material. In that way, the electromagnetic waves can pass through the MNZ material, and some novel radiation characteristics can be obtained.
The metamaterial exhibits more and more novel electromagnetic characteristics, such as the electromagnetic cloak, the frequency selective surface, the energy selective surface, and the like. The metamaterial is widely applied to antenna design, electromagnetic protection and other engineering zones. In this paper, the research on the electromagnetic characteristics of mue near zero (MNZ) material is completed by theoretical analysis and numerical simulation method. Considering a two-dimension MNZ structure, the impedance match between MNZ material and air and the continuity of propagation constant is theoretically analyzed, and it is verified with numerical simulation. It turns out that such characteristic can result in forming plane wave. Also, it is found that a good impedance match can be achieved if the electromagnetic wave parallels to the boundary of MNZ material. In that way, the electromagnetic waves can pass through the MNZ material, and some novel radiation characteristics can be obtained.
2015,
27: 103208.
doi: 10.11884/HPLPB201527.103208
Abstract:
Within the framework of integral equation method, a hybrid approach using equivalent principle is proposed to solve electromagnetic scattering problems. This theoretical model can resolve different relative position of target and the half space surface, including target at either side of the half space surface or the target straddling the surface. Apart from traditional methods using half space Green function to solve scattering problem concerning the existence of half space, the method in this paper uses free space Green function of the two dielectrics which form the half space. Therefore, Somerfield integral can be avoided and be compatible with fast algorithms (MLFMA etc.). Basic theory of equivalent principle is introduced. In this method, an infinite surface is truncated into a finite one, a therefore, tapered incident wave is used to avoid the edge effect. The far field response of a target with a half space background should be expressed as a differential radar cross section. Numerical examples show good agreement with the reference and simulation result from FEKO. The proposed method here can be a tool to analyze the effect of half space on the target nearby.
Within the framework of integral equation method, a hybrid approach using equivalent principle is proposed to solve electromagnetic scattering problems. This theoretical model can resolve different relative position of target and the half space surface, including target at either side of the half space surface or the target straddling the surface. Apart from traditional methods using half space Green function to solve scattering problem concerning the existence of half space, the method in this paper uses free space Green function of the two dielectrics which form the half space. Therefore, Somerfield integral can be avoided and be compatible with fast algorithms (MLFMA etc.). Basic theory of equivalent principle is introduced. In this method, an infinite surface is truncated into a finite one, a therefore, tapered incident wave is used to avoid the edge effect. The far field response of a target with a half space background should be expressed as a differential radar cross section. Numerical examples show good agreement with the reference and simulation result from FEKO. The proposed method here can be a tool to analyze the effect of half space on the target nearby.
2015,
27: 103209.
doi: 10.11884/HPLPB201527.103209
Abstract:
Surface integral equation (SIE) method combined with mode matching (MM) method is used to simulate the radiation problem of aperture antenna with dielectric structure. The mode matching method is used to describe the excitation model of the horn antenna. The metal wall of an aperture antenna is treated as a perfect electric conductor (PEC). The Electric Field Integral Equation (EFIE) is established on PEC. Both of the EFIE and the Magnetic Field Integral Equation (MFIE) are established on the surface which encloses the dielectric structure to form the PMCHW formulation. The combined formulations are solved by using the method of moment (MOM). Two typical numerical examples are given in this article. It shows that the results given by EFIE-PMCHW-MM hybrid method match well with the results given by commercial code FEKO. Furthermore, EFIE-PMCHW-MM hybrid method increases the calculation efficiency and decreases the computer resource consumption than VSIE-MM method.
Surface integral equation (SIE) method combined with mode matching (MM) method is used to simulate the radiation problem of aperture antenna with dielectric structure. The mode matching method is used to describe the excitation model of the horn antenna. The metal wall of an aperture antenna is treated as a perfect electric conductor (PEC). The Electric Field Integral Equation (EFIE) is established on PEC. Both of the EFIE and the Magnetic Field Integral Equation (MFIE) are established on the surface which encloses the dielectric structure to form the PMCHW formulation. The combined formulations are solved by using the method of moment (MOM). Two typical numerical examples are given in this article. It shows that the results given by EFIE-PMCHW-MM hybrid method match well with the results given by commercial code FEKO. Furthermore, EFIE-PMCHW-MM hybrid method increases the calculation efficiency and decreases the computer resource consumption than VSIE-MM method.
2015,
27: 103210.
doi: 10.11884/HPLPB201527.103210
Abstract:
In this paper, an electromagnetic compatibility (EMC) conducted immunity model of a 32 bit digital signal controller (DSC) is presented. The immunity model predicts the susceptibility behavior of a complex microcontroller to conducted disturbances injected through an input buffer. Two major parts of the model, the injection path and power distribution network of input buffers, are detailed according to S-parameter measurement, input output buffer information specification (IBIS) file and non-confidential information. The susceptibility level of the digital signal controller is measured using the direct power injection (DPI) method, and a good agreement between measurements and simulated results is reported in the frequency range from 10 MHz to 1 GHz.
In this paper, an electromagnetic compatibility (EMC) conducted immunity model of a 32 bit digital signal controller (DSC) is presented. The immunity model predicts the susceptibility behavior of a complex microcontroller to conducted disturbances injected through an input buffer. Two major parts of the model, the injection path and power distribution network of input buffers, are detailed according to S-parameter measurement, input output buffer information specification (IBIS) file and non-confidential information. The susceptibility level of the digital signal controller is measured using the direct power injection (DPI) method, and a good agreement between measurements and simulated results is reported in the frequency range from 10 MHz to 1 GHz.
2015,
27: 103211.
doi: 10.11884/HPLPB201527.103211
Abstract:
This paper used the direct power injection method to obtain the conducted immunity of low-dropout linear regulator (LDO) under electromagnetic interference. And a cascade model of linear filters and Taylor series representation of nonlinear system are proposed for immunity simulation. In addition, the traditional modeling method was used to model the linear device on the test system. Finally the immunity simulation of LDO was carried out and the results show that the model in the 1 MHz-2 GHz range has a good fit between simulation and measurement.
This paper used the direct power injection method to obtain the conducted immunity of low-dropout linear regulator (LDO) under electromagnetic interference. And a cascade model of linear filters and Taylor series representation of nonlinear system are proposed for immunity simulation. In addition, the traditional modeling method was used to model the linear device on the test system. Finally the immunity simulation of LDO was carried out and the results show that the model in the 1 MHz-2 GHz range has a good fit between simulation and measurement.
2015,
27: 103212.
doi: 10.11884/HPLPB201527.103212
Abstract:
A method for determining nonlinear large-signal S-parameters from artificial neural network model trained with limited measured data is proposed. Predicted nonlinear S-parameters of a nonlinear device composed of a Schottky diode are in good agreements with measurements. Then the formula for calculating nonlinear S-parameters of network composed of a two-port nonlinear device cascaded with a three-port linear device is deduced, and the application of nonlinear S-parameters in conducted interference analysis is discussed. Finally, the applicability of the proposed method for conducted interference analysis involving nonlinear components is demonstrated by two different cascaded networks.
A method for determining nonlinear large-signal S-parameters from artificial neural network model trained with limited measured data is proposed. Predicted nonlinear S-parameters of a nonlinear device composed of a Schottky diode are in good agreements with measurements. Then the formula for calculating nonlinear S-parameters of network composed of a two-port nonlinear device cascaded with a three-port linear device is deduced, and the application of nonlinear S-parameters in conducted interference analysis is discussed. Finally, the applicability of the proposed method for conducted interference analysis involving nonlinear components is demonstrated by two different cascaded networks.
2015,
27: 103213.
doi: 10.11884/HPLPB201527.103213
Abstract:
The multi-physics simulation algorithm is employed for analyzing the damage of semiconductor devices when high power microwave is injected. The principle and procedure of the multi-physics simulation is briefly introduced. The expression of the carrier ionization rate in the equations of semiconductors physical model is introduced to simulate the avalanche breakdown within Schottky diode. The multi-physics simulation is employed for the analysis of ionization effect and avalanche breakdown of HSMS-282C Schottky diode. The accuracy of the method is validated through comparison of its simulation results with the measurement data. The method can provides useful physical mechanisms for better understanding of the behavior avalanche breakdown within diode.
The multi-physics simulation algorithm is employed for analyzing the damage of semiconductor devices when high power microwave is injected. The principle and procedure of the multi-physics simulation is briefly introduced. The expression of the carrier ionization rate in the equations of semiconductors physical model is introduced to simulate the avalanche breakdown within Schottky diode. The multi-physics simulation is employed for the analysis of ionization effect and avalanche breakdown of HSMS-282C Schottky diode. The accuracy of the method is validated through comparison of its simulation results with the measurement data. The method can provides useful physical mechanisms for better understanding of the behavior avalanche breakdown within diode.
2015,
27: 103214.
doi: 10.11884/HPLPB201527.103214
Abstract:
In complex geographical environment, the irregular terrain influences wave propagation, and different media make different influences on the wave propagation. In order to make the prediction of wave propagation characteristics more accurate and more effective, this paper uses the image segmentation algorithm to realize the classification of the surface media, sets different electromagnetic parameters for different medium and combines with the Digital Elevation Model(DEM) data to build the geographical model that has the terrain fluctuation information and the surface electromagnetic parameters. On this basis, this paper does the grid subdivision to the surface electromagnetic information and uses the parabolic equation(PE) model to predict the wave propagation characteristics in the complex geographical environment.
In complex geographical environment, the irregular terrain influences wave propagation, and different media make different influences on the wave propagation. In order to make the prediction of wave propagation characteristics more accurate and more effective, this paper uses the image segmentation algorithm to realize the classification of the surface media, sets different electromagnetic parameters for different medium and combines with the Digital Elevation Model(DEM) data to build the geographical model that has the terrain fluctuation information and the surface electromagnetic parameters. On this basis, this paper does the grid subdivision to the surface electromagnetic information and uses the parabolic equation(PE) model to predict the wave propagation characteristics in the complex geographical environment.
2015,
27: 103215.
doi: 10.11884/HPLPB201527.103215
Abstract:
This paper studies a novel hybrid method based on Finite Integral method software and transmission line (TL) equations for solving coupling problems of transmission lines in cavity in complicated electromagnetic environment. The software is convenient to build the model of arbitrary cavity without transmission lines and obtain electromagnetic field distribution in the cavity. Electric field probes are used in the software to exact the excited fields of transmission lines. TL equations are used to set up the coupling model of transmission lines in cavity. Then the excited fields are introduced into the TL equations as additional sources. The TL equations discretized by the difference scheme of finite difference time domain (FDTD) method are utilized to compute the current and voltage responses at terminal loads of transmission lines. The correctness of the hybrid method is confirmed by comparing with the results from references and obtained by the traditional method. In testing, the hybrid method in the simulation of coupling of transmission lines in electrically large and complex cavity has high precision and computational efficiency.
This paper studies a novel hybrid method based on Finite Integral method software and transmission line (TL) equations for solving coupling problems of transmission lines in cavity in complicated electromagnetic environment. The software is convenient to build the model of arbitrary cavity without transmission lines and obtain electromagnetic field distribution in the cavity. Electric field probes are used in the software to exact the excited fields of transmission lines. TL equations are used to set up the coupling model of transmission lines in cavity. Then the excited fields are introduced into the TL equations as additional sources. The TL equations discretized by the difference scheme of finite difference time domain (FDTD) method are utilized to compute the current and voltage responses at terminal loads of transmission lines. The correctness of the hybrid method is confirmed by comparing with the results from references and obtained by the traditional method. In testing, the hybrid method in the simulation of coupling of transmission lines in electrically large and complex cavity has high precision and computational efficiency.
2015,
27: 103216.
doi: 10.11884/HPLPB201527.103216
Abstract:
In this paper, a parallel time domain electric field integral equation is applied to numerical simulation of two-dimensional electromagnetic scattering from time-evolving ocean surfaces. The proper choice of temporal basis functions and precise evaluations of matrix elements are used to overcome the late-time instability. Quadratic B-spline function is employed as the temporal basis function, while triangle function is employed as the spatial basis function. The matrix elements are precisely evaluated with analytical formulae for time integrals terms and singular terms. The tapered modulated Gaussian pulse is used to reduce the edge effects resulted from cutting down the infinite sea surfaces. A scheme of message passing interface and compressed storage of sparse matrix are adopted to improve the computational efficiency and reduce the computational storage requirement. Numerical results demonstrate that the method proposed is accurate and efficient for analyzing transient scattering from time-evolving ocean surfaces.
In this paper, a parallel time domain electric field integral equation is applied to numerical simulation of two-dimensional electromagnetic scattering from time-evolving ocean surfaces. The proper choice of temporal basis functions and precise evaluations of matrix elements are used to overcome the late-time instability. Quadratic B-spline function is employed as the temporal basis function, while triangle function is employed as the spatial basis function. The matrix elements are precisely evaluated with analytical formulae for time integrals terms and singular terms. The tapered modulated Gaussian pulse is used to reduce the edge effects resulted from cutting down the infinite sea surfaces. A scheme of message passing interface and compressed storage of sparse matrix are adopted to improve the computational efficiency and reduce the computational storage requirement. Numerical results demonstrate that the method proposed is accurate and efficient for analyzing transient scattering from time-evolving ocean surfaces.
2015,
27: 103217.
doi: 10.11884/HPLPB201527.103217
Abstract:
Research on the electromagnetic environment effect of aircraft has received attention in study of complex electromagnetic environment. With the rapid development of computer technology, using numerical simulation technology to obtain the electromagnetic characteristics of vehicle has become an important means to study aircraft electromagnetic environment effects. This paper demonstrated a massively parallel 3D full-wave electromagnetic field simulation program software JEMS-FDTD and its application to electromagnetic characteristics simulation of a transport plane, and obtained the electromagnetic information in pulse irradiation, such as the time andfrequency domain, and near field/far field and electromagnetic distribution. In order to ensure the accuracy of the calculation, a non-uniform and high order FDTD computing technology was used.
Research on the electromagnetic environment effect of aircraft has received attention in study of complex electromagnetic environment. With the rapid development of computer technology, using numerical simulation technology to obtain the electromagnetic characteristics of vehicle has become an important means to study aircraft electromagnetic environment effects. This paper demonstrated a massively parallel 3D full-wave electromagnetic field simulation program software JEMS-FDTD and its application to electromagnetic characteristics simulation of a transport plane, and obtained the electromagnetic information in pulse irradiation, such as the time andfrequency domain, and near field/far field and electromagnetic distribution. In order to ensure the accuracy of the calculation, a non-uniform and high order FDTD computing technology was used.
2015,
27: 103218.
doi: 10.11884/HPLPB201527.103218
Abstract:
A model of the terahertz waves atmospheric transmission and attenuation is developed with the radiation transmission theory, continuum absorption and modified Van Vleck-Weisskopf line-shape based on the HITRAN database. The THz wave atmospheric attenuation experimental results obtained with the THz-time domain spectroscopy (THz-TDS) technique are analyzed by using this model, and the absorbing attenuation characteristics are compared. The influence of the humidity on the atmospheric attenuation is studied. The precision of the resulted theoretical attenuation is demonstrated by the good agreement between the calculation and the measurement, but a small discrepancy remains in the low-frequency atmospheric window.
A model of the terahertz waves atmospheric transmission and attenuation is developed with the radiation transmission theory, continuum absorption and modified Van Vleck-Weisskopf line-shape based on the HITRAN database. The THz wave atmospheric attenuation experimental results obtained with the THz-time domain spectroscopy (THz-TDS) technique are analyzed by using this model, and the absorbing attenuation characteristics are compared. The influence of the humidity on the atmospheric attenuation is studied. The precision of the resulted theoretical attenuation is demonstrated by the good agreement between the calculation and the measurement, but a small discrepancy remains in the low-frequency atmospheric window.
2015,
27: 103219.
doi: 10.11884/HPLPB201527.103219
Abstract:
This paper proposes a rigorous full-wave solution which combines the mode-matching technique and the mixed potential integral equation based on the method of moments to analyze the shielding effectiveness of the metallic rectangular cascaded enclosure with apertures. Some influence factors, such as the dimension of enclosures, the orientation of apertures, the polarization direction of the incident wave and the high-order modes propagating in enclosures, are considered. The accuracy and the efficiency of the proposed approach are validated by comparing with the classical algorithm. Finally, some conclusions are derived: the shielding performance of cascaded enclosures is better than that of single-stage enclosures, the shielding effectiveness can be improved with increasing the distance between stages in the range, and the shielding performance of the double-stage enclosure with parallel-pattern apertures in horizontal polarization case is better than that in vertical polarization case, but similar advantage is not obvious for enclosures with cross-pattern apertures.
This paper proposes a rigorous full-wave solution which combines the mode-matching technique and the mixed potential integral equation based on the method of moments to analyze the shielding effectiveness of the metallic rectangular cascaded enclosure with apertures. Some influence factors, such as the dimension of enclosures, the orientation of apertures, the polarization direction of the incident wave and the high-order modes propagating in enclosures, are considered. The accuracy and the efficiency of the proposed approach are validated by comparing with the classical algorithm. Finally, some conclusions are derived: the shielding performance of cascaded enclosures is better than that of single-stage enclosures, the shielding effectiveness can be improved with increasing the distance between stages in the range, and the shielding performance of the double-stage enclosure with parallel-pattern apertures in horizontal polarization case is better than that in vertical polarization case, but similar advantage is not obvious for enclosures with cross-pattern apertures.
2015,
27: 103220.
doi: 10.11884/HPLPB201527.103220
Abstract:
The field uniformity of electromagnetic in a pulse excited reverberation chamber was investigated in simulations and experiments. The definition and calculation method were proposed and the results of both aspects were analyzed. The results showed that the field uniformity of pulse excited reverberation chamber is fulfilled with the requirement of IEC standard both in time and frequency domains. The fact that the statistical uniformity field can be built in pulse excited reverberation chamber suggests that the susceptive experiments under electromagnetic pulse field can be performed in reverberation chamber.
The field uniformity of electromagnetic in a pulse excited reverberation chamber was investigated in simulations and experiments. The definition and calculation method were proposed and the results of both aspects were analyzed. The results showed that the field uniformity of pulse excited reverberation chamber is fulfilled with the requirement of IEC standard both in time and frequency domains. The fact that the statistical uniformity field can be built in pulse excited reverberation chamber suggests that the susceptive experiments under electromagnetic pulse field can be performed in reverberation chamber.
2015,
27: 103221.
doi: 10.11884/HPLPB201527.103221
Abstract:
A majority of the high power microwave reflector antennas, which work at high frequency band, employ beam waveguide as feed line. The traditional high power beam waveguide is fed by a high power horn, whose volume is much huger and that the first mirror of the beam waveguide is large. A novel X-band high power microwave feeder with polarization reconfigurable capacity was proposed and simulated. Two phase-correct mirrors were used to transform high power microwave beam to the desired beam, so as to increase power capacity of the window. Two cascaded circular grates were employed to control the polarization of the output beam. And simulation of the feeder was laid out to check the aforementioned design.
A majority of the high power microwave reflector antennas, which work at high frequency band, employ beam waveguide as feed line. The traditional high power beam waveguide is fed by a high power horn, whose volume is much huger and that the first mirror of the beam waveguide is large. A novel X-band high power microwave feeder with polarization reconfigurable capacity was proposed and simulated. Two phase-correct mirrors were used to transform high power microwave beam to the desired beam, so as to increase power capacity of the window. Two cascaded circular grates were employed to control the polarization of the output beam. And simulation of the feeder was laid out to check the aforementioned design.
2015,
27: 103222.
doi: 10.11884/HPLPB201527.103222
Abstract:
The theory of frequency stirred RC is illustrated from the perspective of eigenmodes. According to the frequency domain characteristics of the radiation signal, three effective frequency stirring approaches which can achieve real-time uniform and statistical uniform field environments are systematically researched. A linear sweep signal is selected as the major research object to perform a comprehensive test of the various technical index of frequency stirring RC, including the lowest usable frequency, filed uniformity and statistical properties. The test results prove that the lowest usable frequency in frequency stirring mode is consistent with mechanical stirring, the field uniformity satisfies the tolerance requirement in IEC 61000-4-21 standards, and the electric field obeys the theoretical distribution.
The theory of frequency stirred RC is illustrated from the perspective of eigenmodes. According to the frequency domain characteristics of the radiation signal, three effective frequency stirring approaches which can achieve real-time uniform and statistical uniform field environments are systematically researched. A linear sweep signal is selected as the major research object to perform a comprehensive test of the various technical index of frequency stirring RC, including the lowest usable frequency, filed uniformity and statistical properties. The test results prove that the lowest usable frequency in frequency stirring mode is consistent with mechanical stirring, the field uniformity satisfies the tolerance requirement in IEC 61000-4-21 standards, and the electric field obeys the theoretical distribution.
2015,
27: 103223.
doi: 10.11884/HPLPB201527.103223
Abstract:
In the process of using parabolic reflection to image electromagnetic interference sources, the diffraction-limited system leads to blurred and low resolution images. Interference sources can form into multi-resolution images regionally due to different frequency, so it is difficult to enhance image resolution by using existing super-resolution algorithm. This paper presents an improved Mean Shift algorithm to image adapting to multi-resolution electromagnetic interference sources. On the basis of image segmentation, we partition the multi-resolution images and use a blind deconvolution based on iterative L_R to enhance their resolution. Simulation results show that the algorithm can improve and enhance the resolution of the images formed by multi-resolution interference sources.
In the process of using parabolic reflection to image electromagnetic interference sources, the diffraction-limited system leads to blurred and low resolution images. Interference sources can form into multi-resolution images regionally due to different frequency, so it is difficult to enhance image resolution by using existing super-resolution algorithm. This paper presents an improved Mean Shift algorithm to image adapting to multi-resolution electromagnetic interference sources. On the basis of image segmentation, we partition the multi-resolution images and use a blind deconvolution based on iterative L_R to enhance their resolution. Simulation results show that the algorithm can improve and enhance the resolution of the images formed by multi-resolution interference sources.
2015,
27: 103224.
doi: 10.11884/HPLPB201527.103224
Abstract:
To capture the electromagnetic pulse (EMP) generated by the interaction between laser and target, a loop antenna (B-dot) is chosen as the main EMP signal acquisition device. The signals inside and outside the target chamber are tested simultaneously. This paper focuses on the design and fabrication of antenna and antenna calibration. An EMP diagnostic system is established. The EMP characteristics are investigated by comparing the pulse signals. It turns out that the EMP possessed maximum strength inside the target chamber, followed by the signal on the flange, and it is weakest outside the chamber. Summarizing the multiple EMP frequency spectra, we figure out the crests mainly exist at 0.5, 1.2, 3 GHz. Time-domain EMP distributions regularly demonstrate the pulse lasts about 100 ns. In addition, the EMP signal presents obvious peak clusters at several ns and dozens of ns respectively due to the back oscillation inside the target chamber.
To capture the electromagnetic pulse (EMP) generated by the interaction between laser and target, a loop antenna (B-dot) is chosen as the main EMP signal acquisition device. The signals inside and outside the target chamber are tested simultaneously. This paper focuses on the design and fabrication of antenna and antenna calibration. An EMP diagnostic system is established. The EMP characteristics are investigated by comparing the pulse signals. It turns out that the EMP possessed maximum strength inside the target chamber, followed by the signal on the flange, and it is weakest outside the chamber. Summarizing the multiple EMP frequency spectra, we figure out the crests mainly exist at 0.5, 1.2, 3 GHz. Time-domain EMP distributions regularly demonstrate the pulse lasts about 100 ns. In addition, the EMP signal presents obvious peak clusters at several ns and dozens of ns respectively due to the back oscillation inside the target chamber.
2015,
27: 103225.
doi: 10.11884/HPLPB201527.103225
Abstract:
For most of the magnetic field probes were calibrated in the frequency-domain and could not satisfy the measurement requirement of electromagnetic transient, this paper proposes a time-domain calibration method based on Elman neural network. The method uses Helmholtz coils, surge generators, oscilloscopes and other instruments to build a time-domain calibration platform, and collects the output current of surge generator and the induced voltage of magnetic field probe. The induced voltage and the magnetic induction intensity are taken as the input and output data, then the Elman neural network model is built. The results show that, the model can accurately predict the change tendency of the magnetic induction intensity and the calibration model is effective.
For most of the magnetic field probes were calibrated in the frequency-domain and could not satisfy the measurement requirement of electromagnetic transient, this paper proposes a time-domain calibration method based on Elman neural network. The method uses Helmholtz coils, surge generators, oscilloscopes and other instruments to build a time-domain calibration platform, and collects the output current of surge generator and the induced voltage of magnetic field probe. The induced voltage and the magnetic induction intensity are taken as the input and output data, then the Elman neural network model is built. The results show that, the model can accurately predict the change tendency of the magnetic induction intensity and the calibration model is effective.
2015,
27: 103226.
doi: 10.11884/HPLPB201527.103226
Abstract:
Space discharge is one of the important space stochastic pulse radiation source, and the electromagnetic signals it generates are the interference for frequency equipments such as communication and navigation. A detection system for space discharge radiation signals based on the narrow band test of radiation field is proposed. It consists of directional antennas, high transmission gain receive front-end and recording equipment. A location model of the space plane four-element arrays is built. The rapid search algorithm for space discharge radiation source is researched. And the location precision is tested by experiment. The results show that the system can detect space discharge radiation source within 1 km. the distance location error of space plane four-element arrays with 10 m size is less than 2.5%. The detection and location system can be applied to locating the space discharge source in complex electromagnetic environment, and it is significant for signals recognition and analysis with complex interference.
Space discharge is one of the important space stochastic pulse radiation source, and the electromagnetic signals it generates are the interference for frequency equipments such as communication and navigation. A detection system for space discharge radiation signals based on the narrow band test of radiation field is proposed. It consists of directional antennas, high transmission gain receive front-end and recording equipment. A location model of the space plane four-element arrays is built. The rapid search algorithm for space discharge radiation source is researched. And the location precision is tested by experiment. The results show that the system can detect space discharge radiation source within 1 km. the distance location error of space plane four-element arrays with 10 m size is less than 2.5%. The detection and location system can be applied to locating the space discharge source in complex electromagnetic environment, and it is significant for signals recognition and analysis with complex interference.
2015,
27: 103227.
doi: 10.11884/HPLPB201527.103227
Abstract:
A circuit for detecting arcing in rectangular waveguide is introduced, and the selection of arcing detecting point and photosensitive instruments are analyzed. The conclusions of theoretical analysis and calculations are that the arcing detecting point is chosen in the middle of the rectangular waveguide narrow walls and the photoelectric cell SFH250V is utilized as the photosensitive instrument. Treating SFH250V as the key instrument, an arcing detecting and malfunction fast flip-latch circuit is designed, which solves the problems of weak optical signals detection and weak photocurrent signals conversion and amplification. Meanwhile, the circuit of the arcing malfunction estimation and malfunction signals export is designed. The experimental results indicate that this setup can catch weak arc malfunction signals efficiently.
A circuit for detecting arcing in rectangular waveguide is introduced, and the selection of arcing detecting point and photosensitive instruments are analyzed. The conclusions of theoretical analysis and calculations are that the arcing detecting point is chosen in the middle of the rectangular waveguide narrow walls and the photoelectric cell SFH250V is utilized as the photosensitive instrument. Treating SFH250V as the key instrument, an arcing detecting and malfunction fast flip-latch circuit is designed, which solves the problems of weak optical signals detection and weak photocurrent signals conversion and amplification. Meanwhile, the circuit of the arcing malfunction estimation and malfunction signals export is designed. The experimental results indicate that this setup can catch weak arc malfunction signals efficiently.
2015,
27: 103228.
doi: 10.11884/HPLPB201527.103228
Abstract:
To meet the validation test requirement of a models near-field coupling simulation results, a measurement system based on a fiber electric field sensor was set up. The preliminary test results showed that in some angle range the test results and simulation results followed the same trend. The causes of discrepancy between the two were analyzed. This work laid foundation for the next model optimization and measuring improvement.
To meet the validation test requirement of a models near-field coupling simulation results, a measurement system based on a fiber electric field sensor was set up. The preliminary test results showed that in some angle range the test results and simulation results followed the same trend. The causes of discrepancy between the two were analyzed. This work laid foundation for the next model optimization and measuring improvement.
2015,
27: 103229.
doi: 10.11884/HPLPB201527.103229
Abstract:
In this paper, we introduce a ultra-wideband curving TEM horn, the considerations in product design are mainly power capacity and caliber match. Comparing the ultra-wideband curving TEM horn with the classical invariational-impedance TEM horn, the main structure improvements are coaxial-to-plane converter and curving radiation-plate. The input and radiation characteristics of this two antennas are analyzed. Results are as follows: when the antenna is excited by Gaussian pulse with a pulse width of 960ps, the peak-power transmission efficiency of the coaxial-to-plane converter is 85%. Compared with the invariational-impedance TEM horn, the curving TEM horn has 30% increase at peak-peak electric field radiation, its H-plane directivity diagram is compressed from 80 to 60, furthermore, the transmission and radiation characteristics are improved within 700 MHz, the transient peak-power-capability of the pulse reaches 15 GW. This curving TEM horn is used successfully in the high-power-microwave radiation system of ultra-wideband.
In this paper, we introduce a ultra-wideband curving TEM horn, the considerations in product design are mainly power capacity and caliber match. Comparing the ultra-wideband curving TEM horn with the classical invariational-impedance TEM horn, the main structure improvements are coaxial-to-plane converter and curving radiation-plate. The input and radiation characteristics of this two antennas are analyzed. Results are as follows: when the antenna is excited by Gaussian pulse with a pulse width of 960ps, the peak-power transmission efficiency of the coaxial-to-plane converter is 85%. Compared with the invariational-impedance TEM horn, the curving TEM horn has 30% increase at peak-peak electric field radiation, its H-plane directivity diagram is compressed from 80 to 60, furthermore, the transmission and radiation characteristics are improved within 700 MHz, the transient peak-power-capability of the pulse reaches 15 GW. This curving TEM horn is used successfully in the high-power-microwave radiation system of ultra-wideband.
2015,
27: 103230.
doi: 10.11884/HPLPB201527.103230
Abstract:
The complex electromagnetic environment, under which a type of VHF radio is used in the normal frequency hopping network model is analyzed. Based on the spectrum occupancy, time occupancy, spatial coverage of the electronic equipment, which result in the threat, target and background electromagnetic environments, the quantitative classification standard of the complex electromagnetic environment is proposed. The simple, mild, moderate and severe complex electromagnetic environments are constructed for the VHF radios by using the real radios and simulation technology. The adaptability of the VHF radios is evaluated against different level of the complex electromagnetic environment. The results provide a useful reference for the adaptability test theory study of our electronic equipment to the complex electromagnetic environment in the future.
The complex electromagnetic environment, under which a type of VHF radio is used in the normal frequency hopping network model is analyzed. Based on the spectrum occupancy, time occupancy, spatial coverage of the electronic equipment, which result in the threat, target and background electromagnetic environments, the quantitative classification standard of the complex electromagnetic environment is proposed. The simple, mild, moderate and severe complex electromagnetic environments are constructed for the VHF radios by using the real radios and simulation technology. The adaptability of the VHF radios is evaluated against different level of the complex electromagnetic environment. The results provide a useful reference for the adaptability test theory study of our electronic equipment to the complex electromagnetic environment in the future.
2015,
27: 103231.
doi: 10.11884/HPLPB201527.103231
Abstract:
Aiming at deceptive jamming method based on digital image synthetic (DIS) for inverse synthetic aperture radar imaging, the lack in engineering realization of anti-DIS deceptive jamming method based on variation of frequency modulation rate was analyzed and improved method for anti-DIS deceptive jamming based on compressed sensing theory was put forward. The improved method adopted compressed sampling based on random selecting and sparsity reconstruction method in compressed sensing into signal receiving and processing department in the foregoing method, and engineering practicability for anti-DIS deceptive jamming method based on variation of frequency modulation rate was improved. Simulation revealed validity of the improved method.
Aiming at deceptive jamming method based on digital image synthetic (DIS) for inverse synthetic aperture radar imaging, the lack in engineering realization of anti-DIS deceptive jamming method based on variation of frequency modulation rate was analyzed and improved method for anti-DIS deceptive jamming based on compressed sensing theory was put forward. The improved method adopted compressed sampling based on random selecting and sparsity reconstruction method in compressed sensing into signal receiving and processing department in the foregoing method, and engineering practicability for anti-DIS deceptive jamming method based on variation of frequency modulation rate was improved. Simulation revealed validity of the improved method.
2015,
27: 103232.
doi: 10.11884/HPLPB201527.103232
Abstract:
All-solid-state pulse source with fast-edge requires the feature of miniature, high stability, high repeatability and low power. In order to overcome low power of each pulser, the power synthesis with multi-pitch serpentine microstrip structure is established using ADS simulation software, the effect of power synthesis is confirmed. Using two high stability pulsers as the input of power synthesis module, the module can combine the two low power fast edge dual-exponential signals into one higher power signal. The test results show that the pulser can produce electromagnetic pulse with less than 2 ns falling time of negative pulse, about 10 ns pulse width and 1.1 kV peak voltage; after the two-signal synthesis, the module can produce pulse with 1.6 kV peak voltage, 2 ns falling time and 18 ns pulse width. The method can be extended to multi-pulser synthesis to obtain higher power.
All-solid-state pulse source with fast-edge requires the feature of miniature, high stability, high repeatability and low power. In order to overcome low power of each pulser, the power synthesis with multi-pitch serpentine microstrip structure is established using ADS simulation software, the effect of power synthesis is confirmed. Using two high stability pulsers as the input of power synthesis module, the module can combine the two low power fast edge dual-exponential signals into one higher power signal. The test results show that the pulser can produce electromagnetic pulse with less than 2 ns falling time of negative pulse, about 10 ns pulse width and 1.1 kV peak voltage; after the two-signal synthesis, the module can produce pulse with 1.6 kV peak voltage, 2 ns falling time and 18 ns pulse width. The method can be extended to multi-pulser synthesis to obtain higher power.
2015,
27: 103233.
doi: 10.11884/HPLPB201527.103233
Abstract:
In the optical metamaterials research process, it is extremely important to control and prepare the microstructure of optical metamaterials. This paper roughly reviews the development history of preparation methods of optical metamaterials abroad. The preparation of two-dimensional optical metamaterials was highlighted, while the advantages and disadvantages of various classic preparation methods were analyzed and compared. On the basis of preparation of two-dimensional optics, traditional and new methods of preparing three-dimensional optical metamaterials were further described in this paper. The process ofextracting the effective parameters including electric permittivity, magnetic permeability, refractive index and impedance of optical metamaterials was introduced.
In the optical metamaterials research process, it is extremely important to control and prepare the microstructure of optical metamaterials. This paper roughly reviews the development history of preparation methods of optical metamaterials abroad. The preparation of two-dimensional optical metamaterials was highlighted, while the advantages and disadvantages of various classic preparation methods were analyzed and compared. On the basis of preparation of two-dimensional optics, traditional and new methods of preparing three-dimensional optical metamaterials were further described in this paper. The process ofextracting the effective parameters including electric permittivity, magnetic permeability, refractive index and impedance of optical metamaterials was introduced.
2015,
27: 103234.
doi: 10.11884/HPLPB201527.103234
Abstract:
This paper adopts nitrogen as background gas, pulsed microwave to produce plasmas, another continuous wave as transmission simulation object, and Global Model with diffusion effect to analyze the evolution of electron temperature and density. The discharge pressure of the experiment is 300 Pa. The results of the experiment display that the reception signals of the continuous wave strongly decay in a short time after the beginning of microwave pulse, but the reception signals of the continuous wave recover slowly when the microwave pulse turns off. The microwave transmission is mainly affected by plasma electron density. The results of Global Model show that electron density increases rapidly, even higher than the critical density of discharge microwave, but decreases slowly when the discharge microwave pulse turns off. This means that the diffusion effect is dominant after plasmas at open space lose the sustained energy, so the electron density will not decrease rapidly and the continuous wave is still reflected, until electron density decreases to the value below the critical density of continuous wave frequency.
This paper adopts nitrogen as background gas, pulsed microwave to produce plasmas, another continuous wave as transmission simulation object, and Global Model with diffusion effect to analyze the evolution of electron temperature and density. The discharge pressure of the experiment is 300 Pa. The results of the experiment display that the reception signals of the continuous wave strongly decay in a short time after the beginning of microwave pulse, but the reception signals of the continuous wave recover slowly when the microwave pulse turns off. The microwave transmission is mainly affected by plasma electron density. The results of Global Model show that electron density increases rapidly, even higher than the critical density of discharge microwave, but decreases slowly when the discharge microwave pulse turns off. This means that the diffusion effect is dominant after plasmas at open space lose the sustained energy, so the electron density will not decrease rapidly and the continuous wave is still reflected, until electron density decreases to the value below the critical density of continuous wave frequency.
2015,
27: 103235.
doi: 10.11884/HPLPB201527.103235
Abstract:
To evaluate the anti-jamming capability of a certain continuous wave doppler fuze, an experiment system for fuze irradiation is developed, and typical fuze experiments are performed under ultra-wide spectrum high power microwave (UWSHPM) irradiation. Experiment results show that the strongest coupling pose is when the fuze is vertically upward, and the bomb body axis and the antenna plane are perpendicular to the radiation field propagation direction. The bomb body is the main energy coupling channel. The higher the repetition frequency, the bigger the coupling voltage of the firing circuit. At 82 kV/m field strength, the coupling voltage of the repetition frequency in single, 10 Hz, 20 Hz and 50 Hz states are 66.5, 69.4, 71.5 and 74.6 V, respectively. At 157 kV/m field, the fuze will not be fired in any state. However, the field of UWSHPM can affect the capability parameters, such as demodulation voltage and working current.
To evaluate the anti-jamming capability of a certain continuous wave doppler fuze, an experiment system for fuze irradiation is developed, and typical fuze experiments are performed under ultra-wide spectrum high power microwave (UWSHPM) irradiation. Experiment results show that the strongest coupling pose is when the fuze is vertically upward, and the bomb body axis and the antenna plane are perpendicular to the radiation field propagation direction. The bomb body is the main energy coupling channel. The higher the repetition frequency, the bigger the coupling voltage of the firing circuit. At 82 kV/m field strength, the coupling voltage of the repetition frequency in single, 10 Hz, 20 Hz and 50 Hz states are 66.5, 69.4, 71.5 and 74.6 V, respectively. At 157 kV/m field, the fuze will not be fired in any state. However, the field of UWSHPM can affect the capability parameters, such as demodulation voltage and working current.
2015,
27: 103236.
doi: 10.11884/HPLPB201527.103236
Abstract:
In order to test the safety and reliability of the Unmanned Aerial vehicle (UAV) system under the environment of lightning pulse magnetic field, a certain type of UAV was regarded as the test object. Lightning pulse magnetic field was simulated using the Helmholtz coil and the lightning surge generator. The experimental result shows that the lightning pulse magnetic field of 8/20 s as recommended in the national standard GB50057-94 does not interfere with communication to cause the data link unlock. But three axial magnetic heading sensor is interfered seriously to produce drift and cause reading deviation on known direction. Besides, the polarity of discharge determines variation trend of course angle. After a thorough analysis of mechanism, the magnetic heading sensor can work normally in the linear area by using anisotropic magneto resistance effects regularly changing the resistance value. But the high peak value lightning pulse magnetic field will lead to permalloy resistances disordered arrangement of internal magnetic domain and magnetization, which changes the magnetic sensitivity of sensor and output characteristic, and only appears on the magnetic sensitive direction.
In order to test the safety and reliability of the Unmanned Aerial vehicle (UAV) system under the environment of lightning pulse magnetic field, a certain type of UAV was regarded as the test object. Lightning pulse magnetic field was simulated using the Helmholtz coil and the lightning surge generator. The experimental result shows that the lightning pulse magnetic field of 8/20 s as recommended in the national standard GB50057-94 does not interfere with communication to cause the data link unlock. But three axial magnetic heading sensor is interfered seriously to produce drift and cause reading deviation on known direction. Besides, the polarity of discharge determines variation trend of course angle. After a thorough analysis of mechanism, the magnetic heading sensor can work normally in the linear area by using anisotropic magneto resistance effects regularly changing the resistance value. But the high peak value lightning pulse magnetic field will lead to permalloy resistances disordered arrangement of internal magnetic domain and magnetization, which changes the magnetic sensitivity of sensor and output characteristic, and only appears on the magnetic sensitive direction.
2015,
27: 103237.
doi: 10.11884/HPLPB201527.103237
Abstract:
Redundant design of uplink vice telecontrol is important to ensure UAVs battlefield survivability. In order to test the reliability of the UAVs vice telecontrol datalink system under continuous wave radiation environment, a test platform of UAV continuous wave radiation is established based on continuous wave radiation emission system. The typical effect of unlock is regarded as the basis of interference. The radiation effect on vice telecontrol datalink system is carried out to analyze the effective mechanism of unlock and key coupling path of interference through electromagnetic simulation and injection method. The result shows that, in some sensitive frequency points, vice telecontrol datalink will appear disruption on communication, that performs unlock at the threshold of 0.098V/m. Besides, the electric field threshold of unlock changes with the polarization of the radiation field. Through electromagnetic simulation, it is concluded that the antenna is the main interference coupling path of UAV vice telecontrol system. Analysis shows that harmonics of unlock points contact with the band of UAV. Electromagnetic energy is coupled into the UAV internal transceiver combination through the front door. When the signal to noise ratio (SNR) reaches a certain extent, a demodulated output of bit error rate (BER) is large enough so that the communication interrupts and appears unlock.
Redundant design of uplink vice telecontrol is important to ensure UAVs battlefield survivability. In order to test the reliability of the UAVs vice telecontrol datalink system under continuous wave radiation environment, a test platform of UAV continuous wave radiation is established based on continuous wave radiation emission system. The typical effect of unlock is regarded as the basis of interference. The radiation effect on vice telecontrol datalink system is carried out to analyze the effective mechanism of unlock and key coupling path of interference through electromagnetic simulation and injection method. The result shows that, in some sensitive frequency points, vice telecontrol datalink will appear disruption on communication, that performs unlock at the threshold of 0.098V/m. Besides, the electric field threshold of unlock changes with the polarization of the radiation field. Through electromagnetic simulation, it is concluded that the antenna is the main interference coupling path of UAV vice telecontrol system. Analysis shows that harmonics of unlock points contact with the band of UAV. Electromagnetic energy is coupled into the UAV internal transceiver combination through the front door. When the signal to noise ratio (SNR) reaches a certain extent, a demodulated output of bit error rate (BER) is large enough so that the communication interrupts and appears unlock.
2015,
27: 103238.
doi: 10.11884/HPLPB201527.103238
Abstract:
In the complicated electromagnetic environment, some key devices may be impaired by the nonlinear effect which could reduce the detecting performance of the system, and worst of all result in the failure of the whole system. This paper selects the limiter of one kind of synthetic aperture radar (SAR) to investigate the modeling of nonlinear characteristics and its effect on radar signal processing. Theoretic analysis and computer simulation show that the performance of such a typical electronic system as the SAR under study would be reduced to have bad focusing and low resolving capability by the nonlinear behavior of key devices.
In the complicated electromagnetic environment, some key devices may be impaired by the nonlinear effect which could reduce the detecting performance of the system, and worst of all result in the failure of the whole system. This paper selects the limiter of one kind of synthetic aperture radar (SAR) to investigate the modeling of nonlinear characteristics and its effect on radar signal processing. Theoretic analysis and computer simulation show that the performance of such a typical electronic system as the SAR under study would be reduced to have bad focusing and low resolving capability by the nonlinear behavior of key devices.
2015,
27: 103239.
doi: 10.11884/HPLPB201527.103239
Abstract:
Based on the PIN limiter circuit /device physics mixed mode model, considering the high electric field and high temperature devices multi-physical features under high-power microwave, we simulate the influence of frequency and microwave pulse repetition rate on thermal damage process of PIN limiter. Numerical simulation results show that different frequency microwave pulses damaging the PIN limiter exist a turning point frequency. Microwave pulses near the turning point frequency require more energy or pulse width to damage the device. After one pulse function on the device, the peak temperature of the device declines fast and it is similar to negative exponent relationship. It is easier when the device is in a high temperature. Heat accumulation effect makes it easier on damaging PIN limiter than the single pulse microwave.
Based on the PIN limiter circuit /device physics mixed mode model, considering the high electric field and high temperature devices multi-physical features under high-power microwave, we simulate the influence of frequency and microwave pulse repetition rate on thermal damage process of PIN limiter. Numerical simulation results show that different frequency microwave pulses damaging the PIN limiter exist a turning point frequency. Microwave pulses near the turning point frequency require more energy or pulse width to damage the device. After one pulse function on the device, the peak temperature of the device declines fast and it is similar to negative exponent relationship. It is easier when the device is in a high temperature. Heat accumulation effect makes it easier on damaging PIN limiter than the single pulse microwave.
2015,
27: 103240.
doi: 10.11884/HPLPB201527.103240
Abstract:
By introducing the electronic theory of cable response to X-ray, a Verilog-A model is built to describe the cables character. A circuit model of SPICE is built to calculate the electromagnetism pulse effect of cable under the nuclear explosions radiation. The calculation of the circuit model is much faster than numerical value model. The circuit model can be used to calculate the response of electronic system to X-ray radiation.
By introducing the electronic theory of cable response to X-ray, a Verilog-A model is built to describe the cables character. A circuit model of SPICE is built to calculate the electromagnetism pulse effect of cable under the nuclear explosions radiation. The calculation of the circuit model is much faster than numerical value model. The circuit model can be used to calculate the response of electronic system to X-ray radiation.
2015,
27: 103241.
doi: 10.11884/HPLPB201527.103241
Abstract:
At present, the air defense, anti-ship, air-to-ground missiles all commonly utilize active monopulse radar homing mode, and such precise tracking guidance radar weapons make serious threat to airborne platforms, large ships, and important ground based military targets. To deal with this threat, there is no doubt that the combination of electronic attacks and hard-kill weapons are the best choice, but there are many technical difficulties in the air-based platforms and ships to launch electronic attack to monopulse tracking guidance radar. Aiming at this, the feasibility of electromagnetic interference in polarization field is studied. The mechanism of electromagnetic interference in polarization domain, interference conditions and interference method is analyzed. The results show that the geometry and the reflecting surface and the radiator antenna system are not perfect, radiator off the point and the diffraction phenomenon of reflector caused the cross polarization, radome on incident wave uneven insertion phase delay and transmission coefficient, that the direction of the antenna radome boresight shift appears, increasing the cross polarization level, so the radar precision guided weapon is easily affected by electromagnetic interference in polarization domain. This paper proposes a new electronic attack technique and analyzes the polarization jamming mechanism, jamming condition and methods, and simulates the important technique. This technique urgently needs to enter into actual equipment, and should be attached importance by industry sector.
At present, the air defense, anti-ship, air-to-ground missiles all commonly utilize active monopulse radar homing mode, and such precise tracking guidance radar weapons make serious threat to airborne platforms, large ships, and important ground based military targets. To deal with this threat, there is no doubt that the combination of electronic attacks and hard-kill weapons are the best choice, but there are many technical difficulties in the air-based platforms and ships to launch electronic attack to monopulse tracking guidance radar. Aiming at this, the feasibility of electromagnetic interference in polarization field is studied. The mechanism of electromagnetic interference in polarization domain, interference conditions and interference method is analyzed. The results show that the geometry and the reflecting surface and the radiator antenna system are not perfect, radiator off the point and the diffraction phenomenon of reflector caused the cross polarization, radome on incident wave uneven insertion phase delay and transmission coefficient, that the direction of the antenna radome boresight shift appears, increasing the cross polarization level, so the radar precision guided weapon is easily affected by electromagnetic interference in polarization domain. This paper proposes a new electronic attack technique and analyzes the polarization jamming mechanism, jamming condition and methods, and simulates the important technique. This technique urgently needs to enter into actual equipment, and should be attached importance by industry sector.
2015,
27: 103242.
doi: 10.11884/HPLPB201527.103242
Abstract:
The response of metal-oxide -semiconductor field effect transistor (MOSFET) under high power microwaves (HPMs) is numerically studied by a simulator based on semiconductor drift-diffusion model. Output property and internal response of MOSFET is numerically simulated. Bias voltage may be reduced to less than threshold by the HPM signal injected in to gate electrode and results in a waveform change of output current. Inside the device, electric field intensity in one end of the channel close to the drain electrode is much higher than at the other places, and heat source is concentrated in this zone. In positive semi-cycles peak, the peak value of temperature is in one end of channel close to the drain electrode. In negative semi-cycles, the distribution of temperature tends to be uniform in the middle of the channel. The simulation result can be applied in damage mechanism analysis and design of MOSFET hardening against HPMs.
The response of metal-oxide -semiconductor field effect transistor (MOSFET) under high power microwaves (HPMs) is numerically studied by a simulator based on semiconductor drift-diffusion model. Output property and internal response of MOSFET is numerically simulated. Bias voltage may be reduced to less than threshold by the HPM signal injected in to gate electrode and results in a waveform change of output current. Inside the device, electric field intensity in one end of the channel close to the drain electrode is much higher than at the other places, and heat source is concentrated in this zone. In positive semi-cycles peak, the peak value of temperature is in one end of channel close to the drain electrode. In negative semi-cycles, the distribution of temperature tends to be uniform in the middle of the channel. The simulation result can be applied in damage mechanism analysis and design of MOSFET hardening against HPMs.
2015,
27: 103243.
doi: 10.11884/HPLPB201527.103243
Abstract:
Fuze irradiation experiment data analysis of high power microwave (HPM) electromagnetic pulse is an important problem of HPM electromagnetic effect. The high-dimensional complexity of HPM electromagnetic effect data is the main difficulty of data analysis. HPM electromagnetic effect data on a certain type of radio fuze is analyzed by the fuzzy C mean (FCM)clustering algorithm method, through the design of FCM clustering algorithm. The algorithm processes need several times of iterative computation with the principle of inner class similarity and inter class differences .The optimal classification and the best cluster center of pulse width, peak power, power density of the high power microwave are both obtained. Experimental results show that the optimal clustering center of a fuze under HPM, namely the best interference threshold causing fuze failure can be obtained and the FCM algorithm is validity.
Fuze irradiation experiment data analysis of high power microwave (HPM) electromagnetic pulse is an important problem of HPM electromagnetic effect. The high-dimensional complexity of HPM electromagnetic effect data is the main difficulty of data analysis. HPM electromagnetic effect data on a certain type of radio fuze is analyzed by the fuzzy C mean (FCM)clustering algorithm method, through the design of FCM clustering algorithm. The algorithm processes need several times of iterative computation with the principle of inner class similarity and inter class differences .The optimal classification and the best cluster center of pulse width, peak power, power density of the high power microwave are both obtained. Experimental results show that the optimal clustering center of a fuze under HPM, namely the best interference threshold causing fuze failure can be obtained and the FCM algorithm is validity.
2015,
27: 103244.
doi: 10.11884/HPLPB201527.103244
Abstract:
The coupling of high power microwave into electrical systems, such as airplane, cars, ships, is very complicated. Furthermore, if the incoming wavelength is much smaller compared to enclosure size of target system, the coupling properties of the system depend on its size and shape, the geometry of apertures, and the frequency of the incoming wave. In the short wavelength limit, the nature of the inside electromagnetic field is extremely sensitive to subtle changes in frequency, the shape of the enclosure, and the orientation of the internal devices or cables. At present, even with the fast and powerful computers that utilize efficient 3-D numerical analysis code, addressing this problem is a great challenge because of the numerous CPU resources and computational time. Thus, statistical electromagnetic methods are more appropriate. The stochastic topology approach is a novel statistical method for analyzing system level electromagnetic effects, which combines the BLT topology theory and the random coupling model. This method is able to predict the statistical distribution of induced voltages or currents on components within a system that consists of multiple cavities when excited by short-wavelength interference, such as high power microwave (HPM). Thereby, the probability that the components be disturbed or damaged will be predicted with the threshold data. The general theoretical approach is introduced, and our work on experiments to verify the feasibility and accuracy of this method is presented.
The coupling of high power microwave into electrical systems, such as airplane, cars, ships, is very complicated. Furthermore, if the incoming wavelength is much smaller compared to enclosure size of target system, the coupling properties of the system depend on its size and shape, the geometry of apertures, and the frequency of the incoming wave. In the short wavelength limit, the nature of the inside electromagnetic field is extremely sensitive to subtle changes in frequency, the shape of the enclosure, and the orientation of the internal devices or cables. At present, even with the fast and powerful computers that utilize efficient 3-D numerical analysis code, addressing this problem is a great challenge because of the numerous CPU resources and computational time. Thus, statistical electromagnetic methods are more appropriate. The stochastic topology approach is a novel statistical method for analyzing system level electromagnetic effects, which combines the BLT topology theory and the random coupling model. This method is able to predict the statistical distribution of induced voltages or currents on components within a system that consists of multiple cavities when excited by short-wavelength interference, such as high power microwave (HPM). Thereby, the probability that the components be disturbed or damaged will be predicted with the threshold data. The general theoretical approach is introduced, and our work on experiments to verify the feasibility and accuracy of this method is presented.
2015,
27: 103245.
doi: 10.11884/HPLPB201527.103245
Abstract:
In this paper, the lightweight equipment compartment of full composites which has anti-electromagnetic pulse effectiveness is made using the nickeled-carbon fiber composites skin which uses nickeled-carbon fiber as basic materials, glass fiber composites skin, polyurethane foam and other fittings. In the meantime, the effectiveness of the equipment compartment under HEMP and LEMP is studied. The testing results show that the HEMP shielding effectiveness can achieve 50.1 dB when its rising time is 2.8 ns and half pulse width of the pulse wave is 24 ns; the HEMP shielding effectiveness can achieve 57.2 dB when its rising time is 3.2 s and half pulse width of the pulse wave is 40.3 s.
In this paper, the lightweight equipment compartment of full composites which has anti-electromagnetic pulse effectiveness is made using the nickeled-carbon fiber composites skin which uses nickeled-carbon fiber as basic materials, glass fiber composites skin, polyurethane foam and other fittings. In the meantime, the effectiveness of the equipment compartment under HEMP and LEMP is studied. The testing results show that the HEMP shielding effectiveness can achieve 50.1 dB when its rising time is 2.8 ns and half pulse width of the pulse wave is 24 ns; the HEMP shielding effectiveness can achieve 57.2 dB when its rising time is 3.2 s and half pulse width of the pulse wave is 40.3 s.
2015,
27: 103246.
doi: 10.11884/HPLPB201527.103246
Abstract:
In a complex electromagnetic environment, how to test electronic information equipment is a complex system problem. Meta-synthesis is an effective method to analyze and solve this problem. This method integrates the advantages of reductionism and holism, and gradually develops into a mature system engineering methodology. On the basis of the summary of the method, the generalized problem of electronic equipment test is researched. The complexity of electronic information equipment test in complex electromagnetic environment is studied. The shortage and drawback of the traditional testing method are pointed out. Finally, this paper discusses the implementation process of electronic equipment test by using meta-synthesis method, which provides a new and effective approach for testing electronic information equipment.
In a complex electromagnetic environment, how to test electronic information equipment is a complex system problem. Meta-synthesis is an effective method to analyze and solve this problem. This method integrates the advantages of reductionism and holism, and gradually develops into a mature system engineering methodology. On the basis of the summary of the method, the generalized problem of electronic equipment test is researched. The complexity of electronic information equipment test in complex electromagnetic environment is studied. The shortage and drawback of the traditional testing method are pointed out. Finally, this paper discusses the implementation process of electronic equipment test by using meta-synthesis method, which provides a new and effective approach for testing electronic information equipment.
2015,
27: 103247.
doi: 10.11884/HPLPB201527.103247
Abstract:
For the effect evaluation problem of the multi-false-target jamming against constant false-alarm rate（CFAR） detection radar, the detection threshold of CFAR detection in multi-false-target jamming was studied according to the principle of the CFAR detection, and the jamming effect of the multiple false targets with different interval was analyzed. The conclusion is that the radar with CFAR detection method will output no signal by the effect of the multi-false-target jamming with stated power and density in the specific false alarm probability. At last the simulation was done to prove the analysis. The research can be used to design the multi-false-target jamming.
For the effect evaluation problem of the multi-false-target jamming against constant false-alarm rate（CFAR） detection radar, the detection threshold of CFAR detection in multi-false-target jamming was studied according to the principle of the CFAR detection, and the jamming effect of the multiple false targets with different interval was analyzed. The conclusion is that the radar with CFAR detection method will output no signal by the effect of the multi-false-target jamming with stated power and density in the specific false alarm probability. At last the simulation was done to prove the analysis. The research can be used to design the multi-false-target jamming.
2015,
27: 103248.
doi: 10.11884/HPLPB201527.103248
Abstract:
In order to solve the problem of carrier frequency blind estimation of PSK signals in electronic reconnaissance, a new estimation method was proposed. The phase shift keying(PSK) signal was divided into several overlapping intervals which had equal length, and the spectrum concentration measures of every interval were extracted by the FFT. And then, using the grid-density clustering, the spectrum concentration measures were classified into two categories: the narrowband spectrum interval and the wideband spectrum interval. The narrowband spectrum interval was regarded as the characteristic class. The spectrums of the characteristic class were accumulated to estimate the carrier frequency of PSK signal. The proposed method had avoided the non-linear operation in the traditional PSK signal carrier frequency estimation algorithm. Thus, the signal to noise ratio (SNR) threshold was remarkably decreased. Moreover, the proposed method did not need the prior knowledge of the signal, which was suitable to the electronic reconnaissance occasion. Experimental results had verified the validity of the proposed estimation method in low SNR.
In order to solve the problem of carrier frequency blind estimation of PSK signals in electronic reconnaissance, a new estimation method was proposed. The phase shift keying(PSK) signal was divided into several overlapping intervals which had equal length, and the spectrum concentration measures of every interval were extracted by the FFT. And then, using the grid-density clustering, the spectrum concentration measures were classified into two categories: the narrowband spectrum interval and the wideband spectrum interval. The narrowband spectrum interval was regarded as the characteristic class. The spectrums of the characteristic class were accumulated to estimate the carrier frequency of PSK signal. The proposed method had avoided the non-linear operation in the traditional PSK signal carrier frequency estimation algorithm. Thus, the signal to noise ratio (SNR) threshold was remarkably decreased. Moreover, the proposed method did not need the prior knowledge of the signal, which was suitable to the electronic reconnaissance occasion. Experimental results had verified the validity of the proposed estimation method in low SNR.
2015,
27: 103249.
doi: 10.11884/HPLPB201527.103249
Abstract:
This paper presents a method that aims at selecting the optimal behavioral model and figuring out the fingerprint of the RF power amplifiers. First of all, it introduces the main classification of the behavioral models. Then, regarding Wiener model and Hammerstein model, it proposes an algorithm with a detailed mathematical explanation, which is based on weighted least squares method and obtains the optimal behavioral models successfully. Finally, it presents a numerical simulation for RF power amplifiers in the real world and validates the practicability and effectiveness of the algorithm. In the simulation, firstly the parameters of the behavioral models are computed through the training signals, then the optimal behavioral model is selected by analyzing the errors according to various judgment criteria. The result of numerical simulation reflects the algorithm could obtain the optimal behavioral models of the RF power amplifiers effectively with a relatively small error.
This paper presents a method that aims at selecting the optimal behavioral model and figuring out the fingerprint of the RF power amplifiers. First of all, it introduces the main classification of the behavioral models. Then, regarding Wiener model and Hammerstein model, it proposes an algorithm with a detailed mathematical explanation, which is based on weighted least squares method and obtains the optimal behavioral models successfully. Finally, it presents a numerical simulation for RF power amplifiers in the real world and validates the practicability and effectiveness of the algorithm. In the simulation, firstly the parameters of the behavioral models are computed through the training signals, then the optimal behavioral model is selected by analyzing the errors according to various judgment criteria. The result of numerical simulation reflects the algorithm could obtain the optimal behavioral models of the RF power amplifiers effectively with a relatively small error.
2015,
27: 103250.
doi: 10.11884/HPLPB201527.103250
Abstract:
Blind identification of channel coding is significant for both AMC in cooperative communications and passive listening in a non-cooperative context. Whats more, blind estimation and detection of interleaver parameters is a key step to recover original data sequence. In this paper, we study blind identification of three interleavers block interleaver, convolutional interleaver and helical interleaver, and make some comparison of them. Combining rank criteria with Gauss-Jordan Elimination through pivoting (GJETP) algorithm, blind identification of interleaver parameters in high bit error rate is realized and we discuss the depth, width, synchronization, and step of interleaver respectively. Based on deinterleaver theory and some soft information, a universal method for blind identification of interleaver is raised, which enhances the algorithm ability for adapting to real channel. The experiment indicates that the algorithms are effective and feasible.
Blind identification of channel coding is significant for both AMC in cooperative communications and passive listening in a non-cooperative context. Whats more, blind estimation and detection of interleaver parameters is a key step to recover original data sequence. In this paper, we study blind identification of three interleavers block interleaver, convolutional interleaver and helical interleaver, and make some comparison of them. Combining rank criteria with Gauss-Jordan Elimination through pivoting (GJETP) algorithm, blind identification of interleaver parameters in high bit error rate is realized and we discuss the depth, width, synchronization, and step of interleaver respectively. Based on deinterleaver theory and some soft information, a universal method for blind identification of interleaver is raised, which enhances the algorithm ability for adapting to real channel. The experiment indicates that the algorithms are effective and feasible.
2015,
27: 103251.
doi: 10.11884/HPLPB201527.103251
Abstract:
A new method for frequency hopping (FH) blind signal sorting is proposed based on the character and insufficiency of traditional method for FH separation of network. For the FH asynchronous nonorthogonal netting, the technology of BSS based on the maximum signal noise ratio algorithm is applied to signal sorting. The model of FH blind separation of network is established and a simulation test of signal sorting for multiple FH networks is carried out. Simulation results validate the feasibility of the method and the performance of the blind separation of network for FH asynchronous nonorthogonal netting is given.
A new method for frequency hopping (FH) blind signal sorting is proposed based on the character and insufficiency of traditional method for FH separation of network. For the FH asynchronous nonorthogonal netting, the technology of BSS based on the maximum signal noise ratio algorithm is applied to signal sorting. The model of FH blind separation of network is established and a simulation test of signal sorting for multiple FH networks is carried out. Simulation results validate the feasibility of the method and the performance of the blind separation of network for FH asynchronous nonorthogonal netting is given.
2015,
27: 103252.
doi: 10.11884/HPLPB201527.103252
Abstract:
Usually, the quality of signal will decrease in the multipath signal transmission of high rate modulated signals. In this paper, time reversal arithmetic for multipath signal transmission is researched. According to the known multipath transmission function, by transmitting the time reversal signal, the required signal will focus on the receiver location, thus S/N ratio of signal can be improved, waveform can be optimized, and code error rate can also be reduced, which can mitigate the influence of multipath transmission. This arithmetic is proved to be effective by the injection test.
Usually, the quality of signal will decrease in the multipath signal transmission of high rate modulated signals. In this paper, time reversal arithmetic for multipath signal transmission is researched. According to the known multipath transmission function, by transmitting the time reversal signal, the required signal will focus on the receiver location, thus S/N ratio of signal can be improved, waveform can be optimized, and code error rate can also be reduced, which can mitigate the influence of multipath transmission. This arithmetic is proved to be effective by the injection test.
2015,
27: 103253.
doi: 10.11884/HPLPB201527.103253
Abstract:
As a kind of new concept kinetic weapons in strong magnetic environment, electromagnetic railgun can accelerate macro projectiles to hypervelocity using the electromagnetic force. However, the current distribution in conductors of railguns is sharply uneven, which may affect the system efficiency or the launching reliability. In this paper, as for a kind of complex railguns with copper strips, according to proximity effect about current distribution in conductors, two iron sheathes were added to the sides of the copper strips. A model was proposed, and simulation on current distribution was performed. The simulation results showed that the current in the copper strip was much evenly distributed. All these results are significant to current-carrying capacity of conductors and railguns engineering development.
As a kind of new concept kinetic weapons in strong magnetic environment, electromagnetic railgun can accelerate macro projectiles to hypervelocity using the electromagnetic force. However, the current distribution in conductors of railguns is sharply uneven, which may affect the system efficiency or the launching reliability. In this paper, as for a kind of complex railguns with copper strips, according to proximity effect about current distribution in conductors, two iron sheathes were added to the sides of the copper strips. A model was proposed, and simulation on current distribution was performed. The simulation results showed that the current in the copper strip was much evenly distributed. All these results are significant to current-carrying capacity of conductors and railguns engineering development.
2015,
27: 103254.
doi: 10.11884/HPLPB201527.103254
Abstract:
Left-handed materials (LHMs) present flat lens effect which can enhance evanescent wave by breaking the diffraction limit of electromagnetic wave. And microstrip antenna gain can be improved based on LHMs. In the paper, a dual-frequency microstrip antenna is mentioned. Meander slots are etched on the ground plane to provide the dual-band operation. In order to improve gain of the antenna at the lower frequency, a novel periodic structure of LHMs is designed to cover the antenna. The measurement results show that the gain of microstrip antenna with LHMs is 2.1 dBi and 7.4 dBi at the two bands respectively.
Left-handed materials (LHMs) present flat lens effect which can enhance evanescent wave by breaking the diffraction limit of electromagnetic wave. And microstrip antenna gain can be improved based on LHMs. In the paper, a dual-frequency microstrip antenna is mentioned. Meander slots are etched on the ground plane to provide the dual-band operation. In order to improve gain of the antenna at the lower frequency, a novel periodic structure of LHMs is designed to cover the antenna. The measurement results show that the gain of microstrip antenna with LHMs is 2.1 dBi and 7.4 dBi at the two bands respectively.
2015,
27: 103255.
doi: 10.11884/HPLPB201527.103255
Abstract:
It is difficult to select an optimal atmospheric dry refractivity profile model from the existing models for practical applications. As the atmospheric wet refractivity profile model has a lower precision, the demand to construct an improved model of atmospheric refractivity profile using measured sounding data based on wavelet-based clustering technology and EOF(Empirical Orthogonal Function) analysis method arises. Results showed that the improved model is more accurate than the existing models. The part of dry refractivity profile model can fully consider the local climatic features, and wet part has a higher precision (about 6 unit of atmospheric refractivity) than the existing models by subdividing weather types into four categories. Meanwhile, the weather classification method can be more easily understood by non-meteorological professionals to promote the application of the improved model.
It is difficult to select an optimal atmospheric dry refractivity profile model from the existing models for practical applications. As the atmospheric wet refractivity profile model has a lower precision, the demand to construct an improved model of atmospheric refractivity profile using measured sounding data based on wavelet-based clustering technology and EOF(Empirical Orthogonal Function) analysis method arises. Results showed that the improved model is more accurate than the existing models. The part of dry refractivity profile model can fully consider the local climatic features, and wet part has a higher precision (about 6 unit of atmospheric refractivity) than the existing models by subdividing weather types into four categories. Meanwhile, the weather classification method can be more easily understood by non-meteorological professionals to promote the application of the improved model.
2015,
27: 103256.
doi: 10.11884/HPLPB201527.103256
Abstract:
Performance of electric contact between armature and rails（A-R） developed as armature sliding in railgun bore, in which electromagnetic(EM) characteristics at A-R interface was the fundamental mechanism. Based on transient magnetic field calculation of railgun system, effects of three factors including pulse current, armature velocity, local contact area on evolvement rule of EM characteristics at A-R interface were analyzed. Besides, groups of launching experiments were designed to comprehensively verify the evolvement rule of EM characteristics at A-R interface. Analysis results indicated that, variation of pulse current induced tendency of current concentration towards contact front end, and decreased crowding level of surface current peak region. Armature velocity induced tendency of current concentration towards contact trailing end. Crowding level of current contact trailing end became strengthened as armature velocity increased after 50 m/s, at which current distribution on contact surface was the greatest. Mode of current concentration on the contact surface became U style close to the contact trailing end. Compared with entire surface contact, current density peak was enhanced at various local contact situations, but difference became smaller when local contact area increased or armature velocity increased. Under normal magnetic force, initial contact area would be extended forward. Effect rules above are validated through surface detection of rails and armatures after launching experiments. A-R sliding electric contact mechanism will be deeply studied based on this research results.
Performance of electric contact between armature and rails（A-R） developed as armature sliding in railgun bore, in which electromagnetic(EM) characteristics at A-R interface was the fundamental mechanism. Based on transient magnetic field calculation of railgun system, effects of three factors including pulse current, armature velocity, local contact area on evolvement rule of EM characteristics at A-R interface were analyzed. Besides, groups of launching experiments were designed to comprehensively verify the evolvement rule of EM characteristics at A-R interface. Analysis results indicated that, variation of pulse current induced tendency of current concentration towards contact front end, and decreased crowding level of surface current peak region. Armature velocity induced tendency of current concentration towards contact trailing end. Crowding level of current contact trailing end became strengthened as armature velocity increased after 50 m/s, at which current distribution on contact surface was the greatest. Mode of current concentration on the contact surface became U style close to the contact trailing end. Compared with entire surface contact, current density peak was enhanced at various local contact situations, but difference became smaller when local contact area increased or armature velocity increased. Under normal magnetic force, initial contact area would be extended forward. Effect rules above are validated through surface detection of rails and armatures after launching experiments. A-R sliding electric contact mechanism will be deeply studied based on this research results.
2015,
27: 103257.
doi: 10.11884/HPLPB201527.103257
Abstract:
The problem of calculating electromagnetic quantities of the circuit in the complex cavity is studied in this thesis. A wave chaotic cavity is built, and its radiation and scattering parameters are obtained by testing. Based on RCM, the electromagnetic quantities of the circuit sensitive points are calculated with different microwave pulse width, interval, number and the loss factor. The results of calculation indicate that the coupling electromagnetic energy will be stronger when the target point is irradiated by pulse interference compared to that irradiated by power source. When the pulse energy is fixed, the coupling electromagnetic energy will show certain resonant characteristics with the pulses width, pulse intervals and pulse number, and it will be stronger when the interference pulse number is single compared to several pulse interference. The determination method of the target point more likely affected by electromagnetic interference of circuit is studied by using experiments.
The problem of calculating electromagnetic quantities of the circuit in the complex cavity is studied in this thesis. A wave chaotic cavity is built, and its radiation and scattering parameters are obtained by testing. Based on RCM, the electromagnetic quantities of the circuit sensitive points are calculated with different microwave pulse width, interval, number and the loss factor. The results of calculation indicate that the coupling electromagnetic energy will be stronger when the target point is irradiated by pulse interference compared to that irradiated by power source. When the pulse energy is fixed, the coupling electromagnetic energy will show certain resonant characteristics with the pulses width, pulse intervals and pulse number, and it will be stronger when the interference pulse number is single compared to several pulse interference. The determination method of the target point more likely affected by electromagnetic interference of circuit is studied by using experiments.
