Unidirectional Patch Antenna Without an Extended Ground Plane

A novel unidirectional quasi-patch antenna is proposed whose top surface and the ground plane exhibit the same sizes. Eight metal screws are assembled on the antenna connected with the ground plane as chokes. By adding these screws, good unidirectional radiation is realized in the upper plane. A prototype is fabricated, assembled, and tested. Good impedance matching with a high front-to-back ratio (FTBR) is experimentally validated. The peak realized gain of the proposed antenna is 5.68 dBi in simulation and 4.05 dBi in the measurement. And the measured FTBR is beyond 18.5 dB at the center frequency of 2.045 GHz. The measured FTBR and realized gain demonstrate that the proposed antenna could be a good candidate for devices in the Internet of Things (IoT) ecosystem.