On a simple method of obtaining sidelobe reduction over a wide angular range in one and two dimensions

In many communications and radar applications, one is confronted with interfering signals originating in a predefined angular sector. In such a case, one would like to design the antenna to be insensitive to signals in that angular sector while maintaining high sensitivity in the direction of its main beam. Depending on the particular situation, one may desire that either or both the main beam and the suppressed angular sector be steerable. In treating this design problem, we consider initially the simple case of a one-dimensional linear array of 2N+1 discrete radiating elements. This case was treated in a patent disclosure by Michael A. Kott (1979) in which he described a method for sidelobe cancellation involving the use of an auxiliary interferometer consisting of two elements added to the array, one at each end. It can be shown that the uniform taper is, in a mathematical sense, the ideal taper for Kott's scheme. Extending his work, it is further shown that the entire concept is quite naturally generalized to a two dimensional array with a steerable pencil beam thus providing a suppression region which is independently steerable to any desired position outside the main beam regardless of the beam-steering angle.