Conformal Array Beam Synthesis and Taper Efficiency Comparisons

In order to increase antenna placement options on crowded platforms, three methods for synthesizing conformal phased array excitations on curved surfaces were computer programmed and compared: the Alternating Projections method (AP), the Successive Projections method (SP), and the Genetic Algorithm method (GA). The comparison was based on how closely the synthesized patterns conformed to the desired pattern amplitudes, and on the resulting taper efficiency. An expression for taper efficiency of a curved array was derived, showing directivity compared to a linear array. Greater efficiency would increase gain for a given antenna size. Taper efficiency is useful in evaluating the synthesis methods since different methods can produce very different aperture illuminations despite similarity in the resulting patterns. Curved arrays were computer modeled ranging from 17 to 97 elements. Different initial excitations, element patterns, and desired pattern masks were investigated. The AP method synthesized patterns closest to the desired patterns, closely followed by the GA method. The SP method tended to get stuck in local minima for difficult cases. The GA method was programmed to optimize taper efficiency, but it takes much longer to run than the other two methods.