Design Of Filtering Antenna And Circularly Polarized Antenna Based On Dielectric Resonator

Dielectric resonator antennas(DRA)have attracted a lot of attention owing to their inherent advantages such as compact size,design flexibility,ease of excitation and modes diversity,high radiation efficiency and power capacity.On one hand,high integration and high efficiency radio front-ends play more and more important roles in modern wireless communication systems,and the co-design of filter and antenna has become a very important research topic.On the other hand,many circularly polarized DRAs are suffering from low gain because of the gain of the DRA operating at fundamental mode is usually not satisfying.This thesis focuses on the design of three-pole filtering DRA and dual polarized filtering DRA with low cross-polarization and high isolation,and the design of wideband high gain circularly polarized antenna based on anisotropic DRA.The detail research works are summarized as follows:(1)The design of three-pole filtering DRA with Chebyshev response.Substrate integrated waveguide(SIW)cavities and half wavelength hairpin line resonators are utilized to make up the first and the second resonator respectively,and DRA working at fundamental mode is used to replace the last resonator.Two kinds of filtering antennas are successfully designed.The pass band are 5050 MHz-5480 MHz(<-20 dB)and 4700 MHz-5420 MHz(<-11 dB),and the gain of the filtering antennas in pass band are ~3.9 dBi and ~5 dBi,respectively.Both of them have similar radiation patterns in pass band.(2)The design of differential fed dual polarized DRA with filtering response.DRA is differentially fed by four right triangle SIW cavities and the feeding structure is symmetric.The utilization of SIW not only enhances the bandwidth,but also introduces filtering response.Measured results show that the proposed dual polarized filtering DRA has low cross-polarization(<-30 dB)and high isolation(<-38 dB)in pass band(5150 MHz-5590 MHz).The radiation patterns are also similar over the pass band.(3)The design of wideband high gain circularly polarized anisotropic DRA.Firstly,uniaxial anisotropic structure is utilized to improve the radiation of the side walls,and then gain improvement is achieved.Secondly,spiral micro-strip line with phase delay and cross slot are used to excited two orthogonal fundamental modes with same amplitude but 90 degree phase difference.Finally a wideband and high gain circularly polarized anisotropic DRA is designed,which has an average gain as high as 8dBi in the operating WiMAX band(3.3 GHz-3.8 GHz).