Beam Steering of a Half-Width Microstrip Leaky-Wave Antenna Using Edge Loading

A technique is presented for steering the main beam of a half-width microstrip leaky-wave antenna (LWA) at fixed frequencies over the operational frequency range. By loading the free edge of the microstrip using lumped capacitors, the phase constant may be adjusted in a prescribed manner, and the beam pointed along a desired direction. The transverse resonance method is used to explore the range of capacitances needed to steer the beam through a nearly 90° range of angles for a typical antenna. Measurements of a prototype antenna are used to validate the technique.