On the Thinning of Small Tightly Coupled Arrays

Wideband phased arrays are complex electromagnetic systems. Whether it is electronic warfare, communications, or spectrum sensing, the ability to have ultrawideband (UWB) electronically steerable beams is exceedingly useful [1] . A class of wideband phased array, the tightly coupled array, leverages high levels of coupling between elements and careful trading of reactances to realize wide impedance bandwidth. Most of the unit cell elements in the open literature are based on the dipole, slot, bowtie, Vivaldi [2] , or sliced notch antenna. While extremely versatile, phased arrays sometimes burdened by the T/R modules required to operate over that same UWB; they are often expensive, power hungry, and introduce additional complexities in the integration process. A standard mitigation strategy for some of these in conventional arrays is aperture thinning: de-activation of selected elements in the array. The array methodologies have been extensively studied in the open literature for conventional arrays [3] . However, thinning under the tightly coupled regime lacks the same breadth and depth of study. This work considers the impact that the percentage of elements removed (thinning factor (TF)) has on the performance of a small, all-metal Vivaldi array ( Fig. 1a ), intended for the use as a subarray of a larger array.