Research And Design Of Circularly Polarized Antenna Based On Mode Fusion

With the rapid development of wireless communication systems toward higher frequency bands,the design of broadband antennas has received more and more attention in recent years,and the design methods of broadband antennas have good generality.It is well known that designs based on traveling-wave antennas and self-complementary antennas are an effective method to broaden the antenna bandwidth,however,in these designs,usually only the main mode is excited for radiation,thus limiting the bandwidth of the antenna.With the proposal of multi-mode resonance,a new design concept,that is,the idea of"mode fusion"is proposed.In this design method,in addition to the main mode used for radiation,other higher-order modes are also used for radiation.Thus,the bandwidth of the antenna is further broadened,and it can be seen that this method has important guiding significance for the future broadband high-performance antenna.In this paper,three antennas are designed based on the idea of multi-mode resonance.The details are as follows:1.A circularly polarized antenna based on high-order modes is designed.The resonant frequencies of the three modes are redistributed together by loading slots and metal short-circuit columns to widen the antenna bandwidth.The formation mechanism of circular polarization of antenna is analyzed by equivalent magnetic current method,its 3d B axial ratio bandwidth is in the range of 3.65GHz-3.9GHz.Different from the traditional antenna which utilizes a pair of degenerate modes to form circular polarization characteristics,this antenna utilizes three mutually orthogonal non-degenerate modes to realize circular polarization.2.A broadband circularly polarized antenna based on multi-mode resonance is designed.By loading different forms of parasitic elements,as a result,two new resonance modes are introduced and two axial ratio minima are generated.The 3d B axial ratio bandwidth is in the range of 2.16GHz-2.45GHz,and the maximum gain in its operating frequency band is9.19d Bi.3.A dual-mode resonance-based antenna unit with malleable pattern is designed.By loading a rectangular slot,the pattern of the TM_1,2mode is transformed from the traditional non-broadside radiation characteristic to the broadside radiation characteristic,and introduces a new resonant mode,the TM_3,2 mode,utilizes a metal shorting column and four annular slots to combine the resonant frequencies of the two modes to broaden the antenna bandwidth.Based on the antenna unit,a 2×2 circularly polarized antenna array is designed.In the frequency range of 4.64GHz-5.32GHz,it satisfies|S₁₁|<-10d B,the peak gain reaches9.87d Bi,and the 3d B axial ratio bandwidth is 8.7%.