Research On High Performance A Perture-coupled Dual-Polarized Patch Antenna

Airborne polarimetric synthetic aperture radar(SAR)has become a main means of aircraft detection and guidance with its all-weather high-resolution imaging capability.As one of the key subsystems of SAR,antenna directly affects the receiving sensitivity,imaging resolution,volume and weight of airborne SAR.With the development of antenna technology,many kinds of antennas are applied to airborne SAR.Among them,the aperture coupled dual polarized patch antenna has many advantages,such as light weight,small volume,low profile,easy to realize multi-band share aperture and multi polarization.However,there are still some challenging problems in an aperture coupled dual polarized patch antenna,one is the polarization purity and isolation related to feeding structure,the other is the miniaturization and bandwidth of share aperture related to radiation patch.Therefore,this paper studies the polarization purity,isolation,miniaturization and bandwidth of share aperture of aperture coupled dual polarized patch antenna from two aspects of feeding structure and radiation patch.The main research contents are as follows:Firstly,the aperture coupled dual polarized microstrip patch antenna with opposite side feeding is studied.In order to solve the problem of poor polarization purity of dual polarized microstrip patch antenna caused by the stray radiation of feed network and the radiation of ground edge,an aperture coupled dual polarized microstrip patch antenna loaded with substrate integrated cavity is proposed.Based on the traditional aperture coupled dual polarized microstrip patch antenna,the antenna is loaded with two substrate integrated cavities to suppress the stray radiation of the feed network and the radiation of the ground edge,so as to improve the polarization purity.In order to improve the array layout freedom,an aperture coupled dual polarization microstrip patch antenna loaded by the closed substrate integrated cavity of is proposed.Different from the former antenna,which is loaded with an inside and an outside substrate integrated cavities,this antenna combines the two cavities into one by using coplanar microstrip antenna technology,and applies them to the array and element,respectively,so as to change the resonant structure of the array cavity and make the array arrangement more flexible.The closed substrate integrated cavity can better suppress the radiation from the feed network and ground edge,and further improve the isolation and polarization purity performance.Secondly,the aperture coupled dual polarized metamaterial patch antenna with same side feeding is studied.In order to solve the problem of poor isolation caused by mutual coupling between feed networks in the traditional same side feeding configuration,a stripline fed aperture coupled dual polarized metamaterial patch antenna is proposed.Different from the traditional same side feeding configuration,the feed network of the antenna is arranged in a double-layer ground structure,so that the microstrip line is transformed into a stripline.The substrate integrated waveguide technology is used to suppress the parallel-plate modes that affect the mutual coupling between feed networks,and the metamaterial patch is used to expand the antenna bandwidth,so as to design a broadband dual polarized metamaterial patch with high isolation and high polarization purity.To further improve the degree of freedom of array arrangement,a grounded coplanar waveguide(GCPW)fed aperture coupled dual polarized metamaterial patch antenna is proposed.This is the first application of GCPW feed technology in cross aperture coupled dual polarized patch antenna.Compared with the stripline with three metal layer,feed network based on GCPW only needs two metal layers to achieve dual polarization,thus reducing the antenna complexity and antenna profile.The substrate integrated waveguide structure is used to suppress the parallel plate mode,so as to improve the isolation between ports,and reduce the complexity of feed network and antenna profile.Then,the miniaturized aperture coupled dual polarized metamaterial patch antenna is studied.In view of the limited effect of capacitive loading on the miniaturization of aperture coupled dual polarized metamaterial patch antenna,a reactance loading miniaturized aperture coupled dual polarized metamaterial patch antenna is proposed.According to the principle of metamaterial patch antenna,the propagation constant is proportional to the left-hand capacitance,the right-hand capacitance and the right-hand electric induction.Increasing the above three items can reduce the resonant frequency of the metamaterial patch,In order to achieve miniaturization,the right-hand inductance is increased by etching Jerusalem type slot on the metamaterial patch,and the left-hand capacitance is increased by reducing the unit spacing to increase the propagation constant,so as to achieve miniaturization.To enhance the bandwidth,a miniaturized aperture coupled dual polarized metamaterial patch antenna with low order mode is proposed.This antenna utilizes the characteristic that the main mode of metamaterial patch is related to the number of patch elements.By reducing the number of patch elements,the metamaterial patch works in the low order mode.At the same time,by increasing the dielectric thickness,the right-hand inductance is increased and the quality factor is reduced,so that the antenna can be miniaturized and the working bandwidth can be expanded.Finally,the aperture coupled dual band dual polarized share aperture patch antenna is studied.Aiming at the problem that aperture coupled dual band dual polarization share aperture patch antenna is difficult to realize dual band broadband operation at the same time,a aperture coupled broadband dual band dual polarized share aperture patch antenna is proposed based on metamaterial patch antenna and frequency selective surface technology.In this antenna,the combined unit and microstrip patch are arranged in the same period,coaxial and layered,so that the metamaterial patch can realize three multiplexing.That is to say,the metamaterial patch not only provides a larger working bandwidth as a radiator in the low frequency band,but also provides enough passband bandwidth as a frequency selective surface for the antenna in the high frequency band,As a parasitic patch of microstrip patch antenna in high frequency band,the antenna in high frequency band has a larger bandwidth.In addition,the antenna uses aperture coupled feeding structure with same side feeding and opposite side feeding in low frequency band and high frequency band respectively,which realizes aperture coupled broadband dual band dual polarization share aperture antenna with high isolation and high polarity purity.