A printed radial configuration of width-modulated strip-lines for controlled guided-wave radiation

A new planar leaky-wave antenna (LWA) design that utilizes surface waves (SWs) for leaky wave excitation is presented. Specifically, a directive surface-wave launcher source is employed as the antenna feed generating cylindrical SW field distributions on a grounded dielectric slab. By the addition of a radial configuration of width-modulated printed strips along the azimuth, SW power can be gradually transformed into radiative power. Measured gain values are greater than 10 dBi with the first beam maximum observed at 18.7 GHz in the backward direction 38° from broadside. Frequency beam scanning is also realized over a 4.5 GHz radiating bandwidth from 17.7 to 22.2 GHz. Simulations and measurements are in agreement and results suggest that this LWA structure can offer continuous one-sided beam scanning through broadside from backfire to forward-fire. In addition, the presented radial configuration of width-modulated striplines may also be useful for new guidance structures, printed circuits, and other novel LWA designs operating at microwave and millimeter-wave frequencies.