Experimental Investigations of Adaptive Reactance Parasitic Antenna Dipole Array

Abstract

This work describes a simple, low-cost electrically steerable antenna system suitable for long-distance point-to-point links based on WiFi technology. The antenna consists of a tunable mirror, assembled as an array of closely spaced passive dipoles (scatterers) illuminated by one driven element. The scatterers are arranged in multiple layers that contribute overlapping ranges of phase shift. While collectively providing full 360 degrees of phase range, this approach enables individual scatterers to provide greater amplitude response across narrower phase bands. Smoothness of phase composition is guaranteed by the small spacing between layers (< 0.15λ). Results show that with careful design given the amplitude-phase characteristics of the scatterers, both individually and in aggregates, the antenna can form highly directional beam patterns that are controllable in azimuth and elevation. Experiments demonstrate that an antenna with 500 scatterers, with a 100 cm × 65 cm aperture, achieves 19-22 dBi of gain across 120 degrees of azimuth and 20 degrees of elevation.