Research On X Band Circularly Polarized Antenna Based On SIW Technology

Along with the rapid growth of wireless communication industry,the demand for stable and portable communications equipment in the various walks of life is constantly increasing.As a crucial component in transceiver systems,antenna can accomplish the mutual conversion between signals and electromagnetic waves.Therefore,it plays a decisive role in performance of the entire communication module.Compared with linear polarized(LP)antennas,circularly polarized(CP)antennas can benefit from the effective suppression of the multipath effects,and reduce the loss caused by severe weather.Furthermore,CP antenna do not require precise polarization alignment,so it can be widely used in current radar detection,satellite communications,etc.applications.Substrate Integrated Waveguide(SIW),on the one hand,retains the characteristics of the traditional metal waveguide such as high power,high Q value,and low insertion loss.On the other hand,it also shows the advantages like low loss in higher frequency band,ease of manufacture and integration.Therefore,numerous scholars utilize this technology to design antenna.The Half-mode Substrate Integrated Waveguide(HMSIW)can reduce the volume of the full-mode waveguide by 50%while persevering the corresponding part's field distribution,which provides a promising approach for antenna miniaturization.This paper proposes four SIW CP antennas and analyzes for their generation of CP waves in details.Both fabrication and test are conducted on the antenna.First,a dual-beam dual CP antenna working at 10.9 GHz is proposed.The antenna is designed based on a rectangular resonant cavity operating as TE₂₂₀ mode.By etching the slot on the upper metal surface of the cavity,and then placing four same square metal patches and a cross-shaped patch in the slot,the electric field of the cavity will be perturbed.The antenna can radiate two beams with opposite CP mode simultaneously.The entire antenna is fed by microstrip lines and has single-layer structure,so it can be integrated with most circuits conveniently.On this foundation,combined with the theory of half-mode substrate integrated waveguide(HMSIW),an HMSIW CP antenna and quarter-mode SIW antenna is proposed.The above antennas can reduce the volume of the full-mode antenna by 50%and 75%,respectively.It provides a competitive scheme for antenna miniaturization technique.Finally,based on the principle of the duplexer,a dual-band multi-beam dual CP antenna is proposed.The antenna has an octagonal slot on the top surface.Two sets of square metal patches with different sizes are placed in the slot.The antenna can radiate two CP beams carried opposite rotation simultaneously at 9.6 GHz or 10.8 GHz.Moreover,high isolation can be achieved between two feeding ports.