A Four-Port Square Loop Antenna Integrated with Feeding Network

A low-profile pattern reconfigurable square loop antenna (SLA) is investigated. It is designed by using a single loop element with four ports over hybrid high impedance surface. The simulated and measured results show that, with different excitations, the main lobe in four quadrants and omnidirectional pattern of the presented antenna can be obtained. It exhibits wide bandwidth that covers from 4.8 to 5.48 GHz with a total size of $60\ \text{mm} \times 60\ \text{mm} \times 3.3\ \text{mm}$ . Within the bandwidth, the presented antenna has a maximum gain of 7.1 dBi at 5 GHz. A simple feeding network integrated with the presented antenna that consists of power divider and RF switches is designed for testing and realizing the steerable radiation patterns.