Research On High-performance Circularly Polarized Microstrip Antenna And Array For Millimeter-wave Applications

With the development of the fifth-generation mobile communication technology(5G),wireless communication systems have put forward higher requirements for broadband and large capacity.Because the millimeter wave(MMW)has ultra-wide spectrum resources,it has received widespread attention in the 5G era.As an important communication component,the MMW antenna has an increasing impact on the MMW circuit by its cost,bandwidth and gain.Circular polarization antenna has the advantages of anti-interference and strong mobility.Therefore,high-performance MMW circularly polarized antennas with broadband characteristic have become a research hotspot.In order to improve the traditional microstrip circularly polarized antenna's narrow bandwidth and poor overall performance,this thesis studies the radiation principle of traditional loop microstrip antennas and traditional magnetoelectric dipole(MED)antennas,and designs the microstrip circularly polarized antenna in the 5G MMW frequency band:1.Proposed a MMW broadband dual circularly polarized loop antenna.The antenna is fed by a coaxial line,so that the current passes through a feed ring with a circumference of about 1?₀,and the sequential current phases of 0°,90°,180°,and 270°are provided to the four loading rings,which can realize a five-element loop array antenna.The simulation results show that the proposed loop antenna obtains 12%axial ratio bandwidth(ARBW)(37.2-42GHz),and the gain in ARBW is higher than 6.7d Bic,and the highest gain is 7.8d Bic.2.Proposed a MMW broadband circularly polarized MED antenna.The main radiation part of the antenna is generated by four S-shaped patches,which are connected to the feed ring through four metal pillars.The feed loop composed of four microstrip lines with different characteristic impedances has a strong capacitive coupling effect near the connection point,and the obtained profile height is only 0.1?₀.The simulation results show that the antenna can obtain 32.7%impedance bandwidth(IBM)(23-32GHz),25.7%ARBW(23.7-30.7GHz),and obtain stable gain within the bandwidth.3.Proposed a high-gain broadband circularly polarized array antenna.Using the proposed MED antenna as 2×8 array antenna element,the circular polarization performance of the array antenna under four different sequential rotation arrangements are compared and analyzed in HFSS.After comprehensively considering the loss of the feed network and the performance of circular polarization,the 0° and 90° rotation mode is selected to complete the design of the array.The test results show that the impedance matching of the antenna is less than-10d B in the range of 22.5-31.5GHz,the ARBW is26.9%(22.5-29.5GHz),and the radiation efficiency is better than 70%in the entire working bandwidth.Its 3d B beam width is about 14° in the XOZ plane and 65° in the YOZ plane.