Near field analysis of rectangular aperture antenna under focusing of Gaussian beam

The paper discusses the near field of rectangular aperture antenna under focusing of Gaussian beam by using aperture field method, and obtains the analytic expressions of the near field intensity and gain. Corresponding simulations are conducted under different focusing conditions. The results show that in near field, the nearer the focusing position is from the axis, the bigger the field intensity and gain are, and the field intensity and gain reach their maxima when the focusing position is on the axis. Therefore, the effective range of antenna can be improved by focusing due to its ability to enhance near field intensity and gain of antenna aperture.