Simple weighting to enhance sparse periodic arrays

One of the most promising approaches to construct sparse arrays is sparse periodic arrays. The transmitter, Tx, and receiver, Rx, are constructed with different element spacing, both having grating lobes in the radiation pattern occurring at different angles. These are only partially suppressed in the two-way radiation pattern. We present a simple approach to suppress the grating lobes even further. The enhancement is obtained by forcing zeros in the Tx radiation pattern at the occurrence of the Rx grating lobes and vice versa. Weighting of a few of the outer elements has proven sufficient. Enhancement of 30 dB is found for an array with 64 elements aperture with half the elements active. Only the outer group of elements had non-unity weights. The result is comparable to or better than a dense unity weighted array. If desired, additional weighting can be applied.