Frequency-insensitive phase-shift networks and their use in a wide-bandwidth Butler matrix

It is shown that any desired value of wide-bandwidth constant phase shift can be produced by interconnecting directional couplers and hybrid transformers. This means that band-widths of several octaves are possible. These phase-shift networks are particularly suitable for use in Butler-type multiple-beam-forming matrices, and a wide-bandwidth 16 × 16 port design is given.