Study On Slot-coupled Dual-polarized Microstrip Antenna

It's very important for the system capability of the synthetic aperture radar (SAR) to have a good antenna. The dual-polarized aperture-coupled microstrip antenna has the merits of small size, light weight and conformal ability, so it will bring great advantage once this antenna were used in this field. Nowadays, dual-polarized microstrip antenna has attracted more and more attention.A novel dual-polarized aperture-coupled microstrip antenna is studied in this thesis. With the help of the full-wave simulation CST, we simulate and study the dual-polarized aperture-coupled microstrip antenna and array.Firstly, basic concept of microstrip antenna and its array is described. Several methods are presented for the analysis of aperture coupled micro-strip patch antenna, such as transmission-line method, cavity method, reciprocity method and some used full-wave analysis method. We generalized all kinds of dual-polarized microstrip antenna elements, and compared them each other. Then problem such as widen the operation bandwidth, improve the isolation, suppress the cross-polarization are studied.Secondly, based on the former chapters, the structure of an antenna element is given. The element is fed through two orthogonal H-shaped slots .Then the sensitivity of the geometric parameters which are most critical in the design of element are studied, we gain the plot curve of resonance and input resistance versus frequency, which are basic of the optimization of the antenna. The measured isolation is better than39dB in an operation bandwidth.The further research of eight-element linear array is introduced in chapter 4 of this thesis. We first analyze the availability of the anti-phase feeding technique. The scheme of the antenna array is given. The vertical polarization network is parallel and the horizontal polarization network is series, so the array has a simple configuration. The measured impedance bandwidth (VSWR <2)reach 37.7%for V-port and 26.8%for H-port. Experimental results are in good agreement with the simulation, with high isolation (better than 30.6dB in operation bandwidth) and low cross-polarization characteristics (better than 27.2dB). This linear array can be used as a sub-array of synthetic aperture radar (SAR) system.We finally conclude the research of this thesis with an out look for the further research.