A Millimeter-Wave Spoof-Surface-Plasmon-Polaritons-Fed Dual-Polarized Microstrip Patch Antenna Array

A novel millimeter-wave spoof surface plasmon polaritons (SSPPs)-fed dual-polarized microstrip patch antenna array is proposed in this article. A dual-polarized single-layered square patch antenna fed by SSPPs is investigated first acting as the radiators. A method of directly connecting two orthogonal SSPPs with two edges of the square patch is introduced to excite the TM10 and TM01 modes and to achieve promising performance simultaneously. The fabricated antenna element has a measured overlapped impedance bandwidth of 13.7%, an isolation of more than 15 dB between the two inputs, a gain of up to about 6 dBi, and stable dual-polarized radiation patterns. With the use of two SSPPs branches printed on different sides of the substrate, a compact SSPPs power divider with adjustable power dividing ratio is then investigated for realizing the series SSPPs feed network, whose design considerations are discussed in detail. By combining the feed network with the patch elements, a
$1\times $
4 SSPPs-fed dual-polarized microstrip patch antenna array is fulfilled. The fabricated prototype confirms a bandwidth of 15% and dual-polarized broadside radiations. Benefitted from the simple single-layered geometry without the metallic ground plane over the major region of array geometry and the dual-polarized unidirectional radiation, the presented designs are valuable to emerging millimeter-wave applications.