Miniaturization and Decoupling of Wideband Stacked Patch Antennas Based on Spoof Surface Plasmon Polaritons

The miniaturization and decoupling of wideband stacked patch antennas is first presented in this communication. The miniaturization is achieved by loading spoof surface plasmon polariton (SSPP) structures on nonradiation edges of the stacked patches. Meanwhile, the wideband operation is realized by controlling the difference in propagation constants of the stacked patches. Due to the large propagation constant of the SSPP structures, the size of the antenna is reduced to 0.18 x 0.18 lambda(2)(0), which achieves 72% footprint reduction as compared with the conventional patch antennas on the same substrates. Moreover, both the simulation and measurement show that the proposed miniaturized antenna exhibits a wide bandwidth of more than 16%. To explore its applications in compact multi-input-multi-output (MIMO) systems, a miniaturized wideband decoupling scheme is further proposed by introducing a coupling null at the lower resonant frequency using an SSPP-loaded defected ground structure (DGS). Experimental results show that high isolation larger than 20 dB is achieved over the wide bandwidth with a center-to-center spacing of similar to 0.28 lambda(0).