The design of wideband arrays of closely-spaced wire and slot elements

The quest for wide band operation of antenna arrays, for example reaching 10 to 1 or more, has led to the consideration of many different types of elements. Spirals and other wide band elements have been tried as one alternative, but this leads to large elements with wide interelement spacing that results in grating lobes at high frequencies. In the work of Munk, it was shown that simple dipoles and slots can be effectively used to achieve wide band widths without grating lobes by the effective use and control of element to element coupling and wide band matching techniques. This paper outlines the logic of this array design procedure. Many impedance calculations used in planar wideband array design are made using the periodic moment method code. The theory behind PMM is based on a plane wave expansion technique, and yields the analysis of infinite, periodic, and planar arrays of scattering elements (wires or slots). Semi-infinite calculations are made using a code referred to as SPLAT.