Investigations Of High-Power Lens Antennas For The Azimuthally Symmetric Mode

In recent years, antennas that can directly radiate the azimuthally symmetric mode have been taken into account for the development of high-power microwave(HPM). In order to construct a antenna that radiates a boresight peak(along the longitudinal axis of the source)with high-gain beam , high-power capability and small dimension,two prototype dielectric lenses antennas are proposed,the dielectric lens consists of a number of sectors that locates at the aperture plane of the conical horn,the antenna is featured by the circularly polarized beam and high-power capability. Another antenna which is conical horn with a metal plate lens radiates linear polarized wave. The contents of the dissertation are divided into the fellowing three parts:In part one,the main work is to analyze the far field of pratical antennas. At first,fields in a conical horn are analyzed when the antenna is excited by a circular waveguide TM₀₁ mode,so the aperture fields and aperture phases of the horn are found,radiation fields of the horn are calculated by the equivalent principle. Based on this theory,hyperbolic and elliptical multi-sector lenses are presented,and their far fields and gains are calculated by previous method. Calculations show that the horn with two-sector lens radiates linear polarized wave along the longitudinal axis of the source,while lens with more than two sectors,it radiates circular polarized wave. Modes and fields of metal plates are analyzed,when the metal plates are arranged especially at the aperture plane of the concial horn,and the horn radiates linear polarized wave.In part two,based on self built-up mathematical models,numerical simulation is aimed at designing multi-sector dielectric lens antenna and metal plate lens antenna. Simulations show that the gain of aperture diameter 322.5mm horn with multi-sector dielectric lens deviates within 0.5dB,for length from 300mm to 500mm. In addition,radiation patterns of the horn with different aperture diameters and different lengths are computed when dielectric contant deviates from 2.2 to 2.6,and radiation patterns do not change. Gain of the aperture diameter 312 mm horn with metal plate lens deviates within ldB,for length from 300mm to 500mm,and the gain of the circular contour metal plate lens is lower by 1.4dB than that of the quadrate contour metal plate lens.In part three,antenna was designed and tested not only connecting with low-power signal source but also connecting with high power microwave source. In terms of the measurement method of VSWR(voftage station wave ratio), VSWR measurement device of the circular waveguide TMOi mode was put forward. Reflections and radiation patterns of the antenna excited by probe were measured in the case of low power. Horn with a dielectric lens was also tested under high power situation. Experimental results agree well with the results of analytic theory and numerical simulations.