Butler submatrix feed systems for antenna arrays

Several small order Butler matrices may be interconnected to replace a single large Butler matrix normally employed in beam forming and scanning networks for linear and circular arrays. This permits reduction in the size of the feed system resulting in a saving of system components and hardware. The penalty is an increase in the beamwidth for circular arrays and a reduction in the number of beams for linear arrays. The submatrix feed system has the additional advantage that it can be used to excite arrays with
N
elements (
N \neq 2^{n}
), which normally cannot be fed by a single Butler matrix.