Shaped beam synthesis and conditional thinning for planar phased array

Abstract

A design procedure for a planar phased array pattern is presented. The array is designed to produce a cosecant squared beam along the elevation plane and a pencil beam along the azimuth plane. This design procedure relies on two orthogonal linear array distributions. The linear array distributions are obtained via the use of the Taylor distribution. For the azimuth pattern, a pencil beam distribution is obtained by sampling a 30 dB Taylor distribution. On the other hand, for the elevation pattern, a low side lobe Taylor distribution is used in conjunction with a Woodward type synthesis method to fill the nulls and shape the main beam to the desired beam characteristics. The resulting continuous complex aperture distribution is sampled to obtain the linear elevation discrete array distribution. This technique produces a single continuous complex aperture distribution. The separable rectangular array distribution is formed by the product of two orthogonal linear array distributions. Since the resulting amplitude distribution of the planar array is the product of two sampled linear edge tapered symmetric distributions, corner elements are highly underutilized. Hence, the corners could be lopped off and peripheral elements at the edges be eliminated through a conditional array thinning process. This resulted in an array with a circular boundary, allowing the array to fit conveniently into a circular configuration. The thinned array is physically smaller and reduces the overall cost, size and weight of the antenna. Such an array pattern still maintains its shaped main beam characteristics and well behaved side lobe levels.