Design Of Dual-Polarized Microstrip Planar Array Antenna At Ku-Band

Synthetic Aperture Radar(SAR)is a microwave imaging radar that has a unique advantage in civil and military applications,making it widely used.SAR antenna is one of the important subsystems of SAR system performance,which directly affects the characteristics of SAR system,such as azimuth and range resolution,imaging ambiguity and mapping area.The microstrip antenna becomes an important implementation form of the SAR antenna because of its small size,light weight,low profile,simple process and coplanar integration with the feed network.Dual-polarized antennas increase SAR efficiency as it can generate and accept two signals that do not interfere with each other,and expand the information amount by twice.In this paper,the research on dual-polarized microstrip antennas has the following aspects:1.Introduce the feeding mode of the microstrip a ntenna,the characteristics of polarization and the basic form of implementing dual polarization;Since the final design of this paper is to design a microstrip array antenna,the relevant content of the array antenna is introduced and analyzed,the layout of the feed network in the array antenna design is introduced,and also introduce and select the power splitter in the feed network design.2.Based on the above introduction,the design scheme of Ku-band dual-polarized microstrip antenna unit is given.The antenna center frequency is 15.2 GHz,the operating bandwidth is greater or equal to 1200MHz,VSWR is Less than or equal to 1.6 to 1,and the cross polarization level is less than or equal to-25dB.The antenna adopts a laminated structure and an additional parasitic patch,and has a better polarization isolation and a low cross polarization level through a feeding mode of combination of adjacent coupling and slot coupling,which can realize characteristics of broadband.The gap coupling is achieved by opening an H-shaped groove on the floor,which enables broadband resonance performance and good cross-polarization characteristics,and provides higher coupling efficiency.3.On the basis of the unit design,the design of the 2x2 element dual-polarized microstrip antenna array is completed first,and the feed network of the array adopts the parallel feeding mode.Then use the 2×2 element array as a subarray to design the 24×4 element array antenna,to make the gain reaches 22dB or more,the distance beamwidth is greater than or equal to 127,the azimuth beamwidth is less than or equal to 5',and the distance to sidelobe level is less than or equal to-16dB.The azimuth sidelobe level is-20dB or less.Finally,the antenna array of the 24×4 element is processed and tested,and the performance index of the designed antenna array is obtained to meet the requirements of SAR.