A design of superdirective endfire array in HF band

Superdirectivity has been known to antenna engineers for many years, but there are still few practical applications for the low efficiency, narrow bandwidth and tolerance sensitivity. These difficulties are analyzed and the application of superdirectivity in the HF band is proved to be feasible. Then, the properties of Chebyshev endfire arrays are studied and some principles for HF superdirective endfire array design are given. By these principles, a 3-element superdirective endfire array is designed. The size of this array is much smaller than the conventional Chebyshev array (element spacing is /spl lambda//2) with the same directive gain. More such endfire arrays can be used together in practice to get higher directive gain and narrower beamwidth.