Research On Millimeter-wave Four-arm Circularly Polarized Antenna Based On Integrated Substrate Gap Waveguide (ISGW)

Ka broadband satellite communication is the development direction of satellite communication.Satellite communication is an important support for emergency communication.Circularly polarized antenna can receive electromagnetic waves in any polarization direction,and has the advantage of strong anti-interference ability.Therefore,it is widely used in satellite communication in ka wave band.application.Traditional waveguide structures(microstrip transmission lines,rectangular waveguides,substrate integrated waveguides,and gap waveguides)are designed to have lower gains in Ka-band circularly polarized antennas,which do not meet the requirements for use.Integrated substrate gap waveguides have the advantage of lower loss,so Integrated substrate gap waveguide design for circularly polarized antennas.This article has done the following work:1.An integrated substrate gap waveguide applied in the Ka-band is designed.By analyzing the influence of the size of each part of the periodic arrangement on the impedance characteristics,the designed integrated substrate gap waveguide passband range is 30-40 GH.2.A four-arm circularly polarized antenna based on integrated substrate gap waveguide is designed.In the three-layer integrated substrate gap waveguide structure,the bottom layer has a periodically arranged mushroom-like structure to form a PMC,and the middle layer is a gap layer,and a three-quarter wavelength is designed on the packaged microstrip line below the PEC layer.The ring feeds four antenna anns,each of which is separated by a quarter wavelength,corresponding to a current that produces a phase difference of 90°,thereby producing a circularly polarized wave.A rectangular slit is etched on the upper surface of the integrated substrate gap waveguide for radiating circularly polarized waves.The working principle of the antenna is explained by the electric field distribution and current distribution diagram.The simulation analysis of the parameters was carried out,and the influence of the arm length factor k on the circular polarization effect was analyzed.The relative bandwidth of the antenna reached 21.2%,the gain reached 7.7dB,and the relative axial ratio bandwidth was 8.2%.3.A two-way power splitter based on the loop structure of the integrated substrate gap waveguide is designed.The power splitter uses ISGW as the feed structure,and a loop is designed above the gap layer of the integrated substrate gap waveguide to reduce the coupling between the two ports of the power splitter.Then theoretical derivation,parameter analysis,and finally the circularly polarized antennas are arrayed.The gain of the circularly polarized array antenna after array can be increased from 7dB to 9.7dB,and the relative axial ratio of the array antenna reaches 7.1%.