An electronically scanned antenna using fresnel zone techniques

A novel technique for implementing electronic beam steering of large aperture scattering and receiving arrays is described. The Fresnel zones of an aperture required to form a beam in an arbitrary direction are realized by controlling the output of discrete integrated amplifier-antenna elements distributed over a scattering surface. The analysis of this method of beam forming and scanning considers several important factors such as array patterns, maximum scan ability, and the effect of interelement spacing. Theoretical computer plots have been obtained from the analysis and are compared with experimental results obtained from Fresnel zone plates designed to operate at millimeter wavelengths. Experimental results were also achieved using an array of 21 tunnel diode antenna-amplifier elements.