Research On Circularly Polarized Waveguide Slot Antenna On Single Layer Substrate

Circularly polarized antenna with high gain has always been an important part of the research on antenna.Waveguide slot array is an effective means to realize the antenna with high efficiency and high gain.The substrate integrated waveguide(SIW)slot antenna has the advantages of high gain,high efficiency,simple structure,low cost and easy processing.The radial line slot antenna(RLSA)also owns the characteristics of wideband,good circular polarization and easy making.The antenna uses a single layer substrate to ensure the precision of machining and low cost.Based on SIW slot antennas with single layer and RLSA,this paper discusses the implementation of high gain,circular polarization,broadband and high efficiency,and designs two circularly polarized antenna units and arrays.The main contents of the paper include:Firstly,the research background and the current status of the antenna with good circular polarization,high gain and low profile is discussed,and the different methods for SIW slot antenna to achieve circular polarization are introduced.Meanwhile,the basic development of RLSA is presented from the angles of the origin,classification and comparison,feeding methods and numerical calculation.Secondly,single-layer circularly polarized "?" slot antenna are designed based on SIW and radial waveguides,respectively.A SIW-based 1×8 linear array at 12GHz is designed,the axial ratio bandwidth is about 5.4%,the gain is about 15.0dBic and symmetric rotationally,a center-feeding 1×16 linear array is designed,the axial ratio bandwidth is about 5.2%,the gain is about 18.0dBic.However,when design two-dimensional plane array,the design of the feeding network is complicated.And the sidelobe level and the bandwidth of the array will be worse.In order to solve these problems,the design of the slot antenna based on the radial waveguide is proposed.Meanwhile,the formation theory of circular polarization and the influence of the slot on the coupling factor of the unit are analyzed.Thirdly,aiming at the shortcomings of RLSA modeling and difficulties on design,the improved design method of RLSA is studied.A Ka-band helical arrangement left-handed circularly polarized RLSA is designed.The simple design method that how to divide airs of slot into groups is proposed and the methods of parameter design for controlling the coupling factor and transmission phase is discussed in detail.Then the automatic modeling method using Hfss-Matlab-Api toolkit is discussed,which simplifies the design process.The Ka-band circularly polarized RLSA at 35GHz is designed based on the above technique.Simulated results show that the gain is 30.6dBic at 35GHz and the 3dB gain bandwidth is 7.7%.Besides,the return loss within the bandwidth is less than-20dB,the axial ratio is about 0.4dB,the cross-polarization is about-40.1 dB and the caliber efficiency is 56.4%and the radiation efficiency is 73.4%.Fourthly,an open-boundary RLSA design is proposed because the circular polarization RLSA end-effector is deteriorated and the efficiency is reduced.In order to reduce the end leakage and improve efficiency and the circular polarization performance,the edge of the array is distinguishingly designed.A single layer left-handed circularly polarized RLSA antenna at 12GHz is developed and measured.The simulation and measured gains at 12GHz are 30.6dBic and 28.5dBic,respectively.The axial ratio bandwidth is 10.8%,the caliber efficiency is 67%and the radiation efficiency is 94%.The measured and simulation results are consistent.In this paper,the single-layer circularly polarized waveguide slot antenna is studied.Two kind of left-handed circular polarization RLSAs is designed.They both have the advantages of high gain,circular polarization performance and frequency bandwidth,and the characteristics of low profile,light weight and low processing cost.Therefore;they all have a wide range of applications in the fields of radar system and satellite communication.