Constrained feeds for limited scan arrays

Lossless modular hybrid coupled networks are described for application to phased arrays requiring a few beamwidths of scan. The simplest example of these networks for symmetrical limited scan is easily synthesized from analytical expressions which involve one parameter-the allowed grating lobe level. Formulas and design curves are presented for engineering applications. A practical example is calculated and compared with the conventional discrete subarray approach. Worst case radiation patterns are shown to provide the desired performance. The results show that the present technique in its simplest form requires only about half the number of phase shifters, drivers, and beam steering active devices as a conventional discrete subarray system which provides the same grating lobe level.