The Dumbbell DGS for Reducing Mutual Coupling between Microstrip Circularly Polarized Antennas

In this paper, a dumbbell defected ground structure (DGS) is proposed to reduce the mutual coupling (MC) between circularly polarized (CP) microstrip antennas. By optimizing the dimension of DGS and the distance between DGS and antenna patch, the MC between antenna elements can be reduced by more than 10 dB in the whole operating frequency band. In particular, the MC of the antenna's central frequency decreases by more than 26 dB, and the radiation pattern of the main polarization and axis ratio remain almost unchanged.