A Low-Loss Branching Filter for Broad Widely Spaced Bandwidths (Short Papers)

A waveguide filter which separates the 4-GHz band the combined 4-, 6-, and 11-GHz common-carrier bands with a loss of only 0.05 dB is described. The input is limited to a single polarization, but dual polarizations can be accommodated by using two such filters in combination with a polarization coupler. The filter also has low insertion losses at 6 and 11 GHz: 0.1 dB and 0.06 dB, respectively, a good return loss, 32 dB, and a short length, 2 1/2 ft. Additionally, it has high power-handling capability, good isolation properties, and good mode purity.