Microstrip Array Antenna With Mutual Coupling Suppression Techniques

Due to their unique advantages, such as low-profile, lightweight, easy integration, micorstrip antennas and arrays are widely used in various wireless communication and radar systems. Surface waves are excited in the substrate when microstrip antennas and arrays work. They increase the mutual coupling and decrease the gain of the antennas. Mutual coupling between elements can also cause scanning blindness spots and affect the scanning range in phased arrays.In this paper, researches are preceded based on the questions maintained above. Firstly, we studied the techniques applicated in suppressing mutual coupling between microstrip antenna elements, such as photonic bandgap structure (PBG), electronic bandgap structure (EBG) and high-impedance electromagnetic surfaces. Then, we studied the characteristic, development and application of defected ground structure (DGS). Lastly, we presented to use defected ground structure to suppress mutual coupling, and then decreased the sidelobe and improved the performance of the antenna. The simulated and measured results proved that the proposed DGS can obviously decrease mutual coupling between antenna element in array, reduce the antenna gain and eliminate the scanning blindness spots in phased arrays.The main results are as follows:1. A novel DGS structure is designed and the resistance band characteristics and parameter extraction of the DGS are analyzed. A more accurate model to analyze resistance band characteristics is presented. It provided a more accurate path to analyze resistance band characteristics for the application of the DGS in microstrip antenna array.2. The proposed DGS structure is introduced in a microstrip antenna array. The effect of the DGS structure in suppressing mutual coupling between microstrip antenna array elements is analyzed. Based on the simulated and measured results, an excellent mutual coupling suppression effect is obtained after the DGS is added in ground plane between microstrip antenna array elements.3. The effects of the DGS on scanning spots of the phased array antenna are studied. The scanning characteristic curve is obtained using HFSS software. The research findings indicated that the proposed DGS can effectively suppress the scanning blindness spots in phased array.