Gain and impedance variation in scanned dipole arrays

The effects of mutual coupling on the gain and element impedance of large electronically-scanned arrays of dipoles above a ground plane have been analyzed as a function of scan angle. The resulting calculated gain and impedance variations are tabulated for planar arrays with elements located on a square grid with spacings ranging from 0.5 to 0.8 wavelength, for dipole-to-ground plane heights ranging from to wavelength. The results of the study show that the gain of a dipole array as a function of scan angle depends markedly upon the element-to-element spacing and appears to be quite insensitive to certain other parameters, such as the height of the dipoles above the ground plane. On the other hand, the change in element impedance with scan is considerably affected by some parameters which have little effect on the array gain behavior, and possibilities for minimizing mismatch caused by scanning are pointed out making use of these results.