Wideband Circularly Polarized Patch Array Antenna Based On AMC

Circularly polarized antennas have been applied in wireless communication systems,such as satellite communication systems,WIFI and radio frequency identification technology(RFID).With the rapid development of modern wireless communication technology,more and more microwave bands are assigned to wireless communication standards.Telecommunication is achieved by using a high-gain antenna without increasing the transmit power.Therefore,wideband circularly polarized and high-gain antennas are required for achieving high versatility,good compatibility,and low cost.Recently,artificial magnetic conductor(AMC)is widely applied to improve the performances of antennas,whose structure is simple and easy for fabrication.In this paper,a wideband circularly polarized patch array antennas are designed.First,the electromagnetic and impedance characteristics of AMC are explored.Than,the relation between band gap of reflection phase and the dimensions of AMC is obtained.Besides,The rationale of AMC for bandwidth enhancement is explored,and a required AMC structure is designed.The patch antenna based on AMC exhibits 24% impedance bandwidth.However,a traditional patch antenna has only 6.4% one.Based on that,a 4×4 wideband array antenna based on AMC is designed.The radiating patches are cut with two corners and a rectangular slot for wideband CP radiation.Than,an extra layer of stacked radiating patches is positioned above the initial patches to improve axial ratio(AR)by 2 d B.Finally,a one-to-sixteen wideband feed network is designed.The feed network is positioned under the proposed antenna to reduce the influence for radiation performances.What is more,the feed network is connected with the radiating patches by probes.In this paper,the measured results exhibit impedance bandwidth of 37%(4.40~6.36 GHz),circularly polarized bandwidth of 20%(4.7~5.9 GHz)at AR less than 4 d B.The gain is better than 12 d B within the circularly polarized bandwidth,with the peak gain of 15.3 d B.With the comparison between simulated and measured results,a good agreement is obtained.The both results exhibit good performances,such as wide band,low AR,high gain,low side lobe and symmetric patterns.The measured gain is slightly less than simulated one,because of fabrication error.