Revisiting the Appearance of Grating Lobes for Antennas With Circular Periodicity

This work aims to provide insight into the appearance of grating lobes when the geometry of an antenna exhibits circular periodicity. Examples of such antennas can be uniform circular arrays or rib-deployable umbrella reflectors. The array factor for a single-ring uniform circular array is first analyzed in depth to estimate the location of the grating lobes in both the elevation and azimuth directions. Further, simple analytical expressions are derived to estimate the level of grating lobes that occur nearest to the main beam. We also extend these formulations to predict the behavior of grating lobes when the array elements are arranged in the form of concentric rings, which is more suitable for modeling apertures of antenna that possess circular periodicity.