A new defected ground structure (DGS) is designed to reduce the mutual coupling of a dual-frequency printed monopole array. The designed dual-frequency DGS consists of two concentric split ring slots. Each split ring slot produces band rejection characteristics at one resonant frequency of the antennas. An effective equivalent circuit model of the DGS section is proposed with the circuit parameters successfully extracted. Good agreement exists among the circuit simulation, EM simulation and experimental results. With the inclusion of the DGS, the measured mutual coupling of the dual-band array has been effectively reduced by 10 dB and 20 dB at two resonant frequencies, respectively.
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