Low-profile inductance-loaded square loop antenna with steerable beam

A low-profile beam steerable square loop antenna (SLA) is presented. The antenna is designed with square metallic loop and hybrid high impedance surface (HHIS) printed on the top and center layers of the substrate. By exciting four feeds that connected to each arm of the loop individually or simultaneously, the antenna achieves beam steerable. In order to expand operating bandwidth, the loop is loaded with narrow metallic strips that serve as inductances in the corner of the four arms. Simulation results show that the impedance bandwidth covers from 4.2 GHz to 5.7 GHz. Within this bandwidth, the SLA have a maximum gain of 9.5 dBi if only one feed is excited, and it provides semi-doughnut radiation pattern with gains between 3 to 5 dBi while all four feeds are excited.