Analysis of radiation pattern effects in sequentially rotated arrays

Sequentially rotated feeding of circularly polarised arrays gives improved main beam cross polarisation rejection, VSWR and bandwidth. However, when excitation errors are present, significant grating lobes are present which may limit system bandwidth. The paper examines the radiation pattern behaviour of such arrays. After discussing array excitation error sources, a simplified analysis is presented that allows prediction of the grating lobe position and height. Two practical cases are then described that illustrate the issues and application of the analysis