Ambiguity patterns of planar antenna arrays of parallel elements

To investigate the suitability of antenna array geometries for direction finding an ambiguity function, essentially the MUSIC function for a single signal, is introduced. This is closely related to the array gain pattern evaluated over the upper hemisphere, for all array steered directions. For a general array the domain of the function is four dimensional but for a planar array of parallel elements this reduces to two dimensions and can be evaluated easily. Ambiguity patterns for some circular and nearly circular arrays are presented showing considerable differences in ambiguity for small differences in geometry