改进型COBRA透镜天线的设计
Design of improved COBRA lens antenna
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摘要: 设计了X波段COBRA透镜型天线,利用电磁波在不同介质传播速度的差异,通过放置于圆锥喇叭口径处不同厚度的介质透镜改变TM01模不同扇区的相位,从而改变TM01模在普通喇叭口径处的轴对称分布,将轴对称的口径场分布转换为线对称,进而实现线极化或圆极化的轴向辐射。通过添加匹配介质,减小介质对微波的反射和驻波特性的影响;延伸喇叭到透镜边缘,使移相过程在波导内完成,有效地控制了电磁场模式。天线增益在中心工作频率为9.3 GHz时为19 dB,口径效率25%,辐射效率大于90%,反射系数小于1.3,轴比小于2 dB, 3 dB相对带宽大于30%,几乎可以覆盖整个X波段。Abstract: An improved COBRA lens antenna in X-band for TM01 mode is designed. The dielectric lens consisting of three or four sectors is located on the aperture plane of a conical horn. The antenna can radiate circular polarzied patterns, with a boresight peak and a high gain. The results of simulation demonstrate that at the operating frequency, the gain, the aperture efficiency and the radial efficiency are 19 dB, 25%, and more than 90% respectively. The axial ratio is less than 2 dB and the relative band-width of 3 dB is more than 30%, which covers almost the whole X-band.
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Key words:
- tm01 mode /
- cobra lens antenna /
- circular polarized pattern
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