Research On Loop Slot Antenna Based On SIW Structure

Circularly polarized antennas can suppress multipath interference and reduce polarization mismatch,and have been widely used in various wireless systems.And wide-beam circularly polarized antennas have a larger angular coverage,which can enhance the reliability of communication systems using such antennas.In addition,multi-frequency antennas can be used for full-duplex communication to reduce network latency,while also reducing interference between antennas within the same communication system.Based on the substrate integrated waveguide structure,this thesis studies and analyzes these two antennas.The main work is summarized as follows:1.A wide-beam circularly polarized antenna is designed based on the substrate integrated waveguide structure.This thesis first analyzes the principle of realizing wide-axis ratio beam.In the specific analysis,it is found that the electrical lengthM?₀ is an important parameter affecting the beam width,Moreover,there is an optimal value of the electrical lengthM?₀ to maximize the beam width.Then a"stepped"stub was introduced to increase the electrical length M?₀,In order to make the electrical lengthM?₀ closer to the optimal value,chamfering the gap makes the rectangular ring gap into an octagonal ring gap.Finally,its axial ratio beamwidth reaches more than 180°.2.A dual-frequency circularly polarized antenna is designed based on the substrate integrated waveguide structure.There are multiple modes in the substrate integrated waveguide cavity,and choosing to excite different modes can make the antenna achieve different performances.When multiple modes are excited at the same time,it is possible to achieve circular polarization at the intermediate frequency point of the two modes,and it is also possible to achieve a wide frequency band.In the specific analysis and design,multiple modes were first excited,and two of them were selected to realize dual-frequency circularly polarized radiation.Then,the resonant frequency of the antenna is changed by scaling technology,so that the two frequency bands that realize circularly polarized radiation are more spaced apart and the frequency ratio is increased.