Estimation of actual direction of arrival for ellipsoidal dielectric lens array antenna

A cost effective smart antenna can be implemented by exciting a shaped dielectric lens by an array antenna. However a drawback of this system is the estimation of Actual Direction of Arrival (ADOA), since the incoming rays have been refracted by the shaped dielectric lens. The array antenna employs DOA algorithms, specifically Multiple Signal Classification (MUSIC) to estimate Virtual Direction of Arrival (VDOA). These estimated virtual angles need to be compensated for the refractive effect of the lens to obtain ADOA in real time. Geometrical optics is employed to trace the rays from the front of a lens, through the shaped lens boundaries to the individual antenna elements to determine the MUSIC computed VDOA angles of the incoming signal. To extract the ADOA a simple pre-computed look up table using `Adaptive angular compensation for modified wavefront´ is presented for the elevation and azimuthal planes. Further this procedure is extended to detect the onset of partial blindness due to total internal reflection. The study has been carried out for an ellipsoidal dielectric lens excited by a 4×4 planar array operating at 10GHz.