| The FMCW(Frequency Modulated Continuous Wave) SAR is increasingly being used on the air-born imaging system for its advantages of low-power consumption, light weight, high accuracy, etc. The full-polarization radar has an excellent ability to recognize the target because of its greater sum of information. Based on the requirement of the ariborn FMCW full-polarized SAR imaging system, especially the working mechanism of the radar antenna feed system, the research on the Ku band dual-polarized Transmit/Receive microstrip array antenna is taken in this paper.The main works in this thesis are listed as follows:Firstly, the proper antenna unit is chosen according to the theoretical analysis and simulation. The coplanar microstrip-fed square patch is utilized to ensure the high gain within the working band. The 3 × 2 subarray module is designed to restrain the cross-polarized radiation. The horizontal & vertical feed network are designed in different strip line layers, the metalized hole structure is set around the main network in order to improve the cross polarization isolation. The testing results shows that the VSWR of the ports are lower than 1.6, the gain is higher than 21.4d B, and the cross polarization in the main lobe is better than-25 d B within the 8% relative bandwidth.Secondly, the choke groove& low isolated wall is designed to realize the high T/R isolation property required for the FMCW system. The T/R isolation which is better than-55 d B is obtained without any degradation to the radiation property. In addition, the wedge-shaped matching structure is designed to realize the detachable property of the T/R array antenna. Moreover, in order to reduce the weight of the antenna, the metal material and the mechanical structure are specially designed.The testing results prove that the optimized design schemes listed above obtain good effects, the Ku band dual-polarization array antenna is capable of being used in the FMCW SAR imaging system. |
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