Planar antenna for continuous beam scanning and broadside radiation by selective surface wave suppression

A printed leaky-wave antenna (LWA) based on a grating of concentric annular microstrip rings fed by a non-directive TM0 surface-wave launcher (SWL) is presented for two-sided continuous beam scanning and broadside radiation. By appropriate selection of the grating periodicity 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 a 3 dB beamwidth less than 6° at 17.9 GHz. The presented LWA may be useful for radar and surveillance systems where continuous beam scanning through broadside is desired.