Research And Implementation Of Waveguide Slot Antenna Based On Spherical Resonator

Waveguide slot antennas are widely used in radar detection,ship navigation and other systems duo to their advantages of stable structure,low loss and high power handling capability.This thesis first introduces the development history and research status of waveguide slot antennas based on rectangular and cylindrical waveguides,sorts out their advantages and disadvantages,and then studies the theoretical basis and radiation principles of slot antennas.Based on this,a design method of slot antenna based on spherical resonator is proposed.The main research contents and innovations of this thesis are as follows:1.The electromagnetic field distribution,resonance frequency and surface current distribution of the modes of the spherical resonator are studied,and a dual-band slot antenna based on the spherical resonator is designed and implemented.By simultaneously radiating the fundamental mode TM101 and the first high-order mode TM211 of the spherical resonator,the antenna can not only achieves dual-band characteristics,but also maintains good radiation performance in two operating bands.Measured results show that,in the lower band,the center frequency of the antenna is 10.2 GHz,the absolute impedance bandwidth is 0.8 GHz with S11 lower than-10 d B,and the relative bandwidth is 7.8%.In the upper band,the center frequency of the antenna is 14.3 GHz,the absolute impedance bandwidth is 2 GHz with S11 lower than-10 d B,and the relative bandwidth is 14.2%.The peak gains of the antenna in the lower and higher bands are 8.8 and 10.2 d Bi,respectively.In addition,the antenna can achieve stable directional radiation characteristics and low cross-polarization in both bands.2.A wideband slot antenna based on spherical resonator is designed and implemented.By simultaneously radiating the modes TM101 and TM211 and coupling their resonance frequencies to each other,the impedance bandwidth of the antenna is significantly improved but without sacrificing the radiation performance.Measured results show that the-10 d B bandwidth is from 9.77 to 14.81 GHz,the absolute bandwidth is 5.04 GHz,and the relative bandwidth is 40.9%.The average gain of the antenna is about 10.2 d Bi,and the total efficiency in the operating band is higher than 90%.3.A dual-polarized slot antenna based on the spherical resonator is designed.By loading two rectangular feeding waveguides on the spherical resonator,two electric fields with orthogonal polarization direction are excited.Next,by loading a "cross" slot on the resonator,the antenna can achieve dual polarization characteristic.Simulated results show that the proposed antenna can radiate electromagnetic waves in horizontal and vertical polarization directions,and has the same maximum radiation direction when it works in two polarization states.Within the operating bandwidth,the gain of the antenna is flat and stable,and the isolation between the two ports is better than-22 dB.