Short-circuited feed terminations on beam steering square loop antennas

Theoretical and experimental investigations of a beam steerable square loop antenna (SLA), including a four-port practical feeding mechanism, is presented. Exciting one of the feeds and short-circuiting the other three results in a linearly polarised beam tilted up from the ground plane and directed away from the active feed. Thus, by exciting one feed at a time, the antenna steers the beam in four different quadrants. A qualitative explanation of the radiation characteristics is also presented using the current distribution. The SLA is designed to operate at 4.5 GHz and has a gain of 6.7 dBi.