Ultrawideband Spoof Surface Plasmon Polariton Bidirectional Endfire Antenna Based on Wave Vectors Mismatching

In this work, an ultrawideband spoof surface plasmon polariton (SPP) bidirectional endfire antenna is proposed based on wave vectors’ mismatching. One splitter structure connects two radiator structures to form the proposed antenna, and two types of slot lines are used to design the splitter structure and the two radiator structures. Although the spoof SPP can transmit to the two radiator structures from the splitter structure, the wave vectors of the spoof SPP in the splitter structure and radiator structures are mismatched. Thus, the spoof SPP from the splitter structure will not be bounded mode when it propagates at the two radiator structures and will be decoupled by the two radiator structures, thereby realizing a bidirectional endfire radiation pattern. The bandwidth of the proposed antenna depends on the decoupling bandwidth of the spoof SPP based on wave vectors’ mismatching, which is determined by the working band of the splitter structure and the dispersion of radiator structures. This proposed antenna has a relative bandwidth of 120% from 9.6 to 40.00 GHz, average efficiency of 93%, and an average gain of over 9.2 dB, having great potential in microwave and millimeter communications.