Forward and backward leaky wave radiation with large effective aperture from an electronically tunable textured surface

A resonant texture allows the impedance of a metal surface to be changed from an electric conductor to a magnetic conductor, or any boundary condition in between. Varactor diodes in corporated into the structure allow electronic control the reflection phase and the surface wave properties. This tunable textured surface is used as an electronically steerable leaky wave antenna, by coupling energy into a leaky wave band, and tuning the surface to change the radiation angle. With a simple optimization algorithm, the beam can be electronically scanned over a wide range in both the forward and backward directions. Because the surface geometry provides multiple degrees of freedom per half wavelength, it allows independent control of the magnitude and phase of the surface wave radiation, so the antenna can be programmed to have a large effective aperture over the entire scan range. Radiation in the backward direction can also be understood in terms of a backward band, which can be measured directly from the surface reflection properties.