A sectored planar periodic leaky-wave antenna fed by a printed surface-wave source

A planar leaky-wave antenna based on a grating of concentric annular microstrip rings fed by a non-directive TM0 surface-wave launcher is presented for two-sided continuous beam scanning and directive radiation at broadside. By appropriate selection of the grating periodicity and sectoring of the 2-D guiding structure, TE field distributions can be suppressed over a large bandwidth ensuring efficient TM0 leakage and radiation into the far-field. Measured results demonstrate a pencil beam at broadside with gain values greater than 15 dBi, making the design attractive for radar systems and communication applications. More importantly, the investigated techniques for TM unimodal operation can also be applied to other guidance structures where unwanted TE field excitation may be of concern at microwave and millimeter-wave frequencies.