Mutual coupling suppression of closely spaced microstrip antennas by ladder-shaped conducting wall

摘要

To reduce the mutual coupling between two closely microstrip antennas (MSAs), a novel ladder-shaped conducting wall structure (LSCW) has been proposed and presented in this paper. This structure consists of two ladder shaped strips of copper printed on an FR-4 dielectric substrate. It is inserted between the MSAs, and also some part of LSCW surrounds a portion of each antenna. The developed compact multiple-input multiple-output system has a compact size of 50 x 25 mm(2), and dual-band design resonates at 4.45 or 10.3-GHz frequencies depending on the dimensions of LSCW structure. It can be used in many wireless applications in C (4-8 GHz) band or X (8-12 GHz) band. The value of VSWR = 1.5 for both resonant frequencies. Also, the diversity performance, such as the envelope correlation coefficient, the diversity gain, and the total efficiency are calculated and compared. A prototype is fabricated, and the measured mutual coupling shows that the isolation between the antenna ports has been enhanced about 50 dB at 4.45 GHz and 40 dB at 10.3 GHz.