Adaptive reactance parasitic antenna array

This paper presents initial experiences with the design and implementation of a low-cost beam steering antenna for long-distance WIFI applications. The antenna system has three components: (1) an adaptive parabolic reflector constructed from an array of passive scatterers with tunable reactive loads, (2) an optimizer that runs on a host computer that adjusts the phases and amplitudes of their currents based on received signal strengths, and (3) a minimal hardware controller that interfaces to an array of digital-to-analog converters and varactor bias voltage logic. Experimental measurements confirm electrodynamics simulations and show that highly directional patterns can be realized while controlling orientation in azimuth and elevation. Initial results achieve 18 dBi of gain across an operational 50 degrees of azimuth with a beam width of 10 degrees. Higher gains of 22 dBi or more are possible with reduced range of steerability.