Array steering compensation for the presence of shaped dielectric lenses

Smart antennas involves processing to manipulate the signals induced on various antenna elements to accomplish beam steering and improve interference rejection. The directive gain of such arrays can be further enhanced by introducing shaped dielectric lens, which also seals the array from environmental effects. In this paper we present a study on the compensation to the array steering algorithms viz; direction of arrival (DOA) and Adaptive Beam Forming (ABF) for an array - shaped dielectric lens combination. Geometrical optics is employed to trace the rays from the individual antenna elements through the shaped lens boundaries to an aperture in front of the lens. Two array steering algorithms viz; Minimum Variance Distortionless Response (MVDR) and Multiple Signal Classification (MUSIC) have been investigated in detail for array steering in the presence of three types of shaped dielectric lenses. Angle dependant modifications have been introduced in the algorithms that correct for the refractive effects of the lens and extract the actual angle of arrival. It is also shown that the use of lens results in better resolution due to the collimation; apart from the benefit of far fewer number of array elements.