Research On Dielectric Resonator Antennas With Wide Beamwidths

Dielectric resonator antennas(DRA)have the advantages of traditional microstrip antennas,and their losses hardly increase with the increase of frequency,so they have gradually attracted attention.Dielectric resonators have been used in the design of filters and oscillators in microstrip circuits,and they are known as an energy storage element.Until1983,after Long designed a cylindrical DRA,more and more research on dielectric resonator antennas.In recent years,in the application fields of satellite communication and phased array radar,the requirements for the antenna beam width have become higher and higher.Therefore,the research on the wide beam antenna is of great practical significance.This thesis mainly researches the wide beam dielectric resonator antenna.The research results of this thesis can be summarized into the following two points:1.A wide beamwidth rectangular dielectric resonator antenna(RDRA)working on dual modes is proposed in this letter.The radiator of the antenna with inside metallic posts and outside metallic walls is placed on a groundplane with a size of 2?_g×2?_g.A?mode,which is similar tomode,is generated by using the metallic posts inside the DR.By adjusting the height of metallic posts and the distance between the DRA and the metallic walls,the?mode,and themode are superimposed with each other,widening the beamwidth of the RDRA to above 140 degrees in both the E-plane and H-plane.In this thesis,the superposition principle of the two patterns and the effect of adding metal walls on the two sides of the dielectric resonator are analyzed.This antenna works from 8.1 GHz to8.7GHz with a relative bandwidth of 7.1%,which can be a good candidate in navigational systems.2.Based on the theory of rectangular dielectric resonator antenna and circular polarization theory,a wide beam circularly polarized dielectric resonator antenna is designed.In order to realize the circular polarization characteristic of the rectangular dielectric resonator antenna,two ports with a phase difference of 90 degrees are used to feed on two adjacent sides of the RDRA.The power is divided equally between the two ports by designing a two-strip microstrip circuit,and a 90-degree phase difference is achieved by designing the length of the microstrip line.Broaden the beamwidth by adding four metal branches to the four corners of the ground plane.The four metal branches are equivalent to four dipole antennas perpendicular to the ground plane.This thesis studies the influence of the length and height of metal branches on the antenna's radiation pattern,and uses MATLAB to simulate the variation of the antenna'radiation pattern of the equivalent dipole antennas with the elements'distance.By considering the influence of multiple variables,the suitable parameters are selected to realize the wide beamwidth.The simulation results are in good agreement with the measured ones.The axial ratio bandwidth of the antenna is3.93GHz-4.1GHz,and the half-power beamwidth of the antenna in the axial ratio bandwidth is broadened to about 180 degrees.