GB818450A - Microwave diplexer - Google Patents

Abstract

818,450. Phase-shifting networks. SPERRY RAND CORPORATION. July 8, 1955 [July 9, 1954], No. 19904/55. Drawings to Specification. Class 40 (8). In a waveguide diplexing arrangement, two signals of different frequencies are applied together at a single input and appear separately at two outputs. Alternatively, two signals of different frequencies may be fed into the arrangement at separate inputs so as to leave at a single output. The arrangement consists of two hollow, rectangular section waveguides which are connected together at two positions along their length by hybrid directional couplers. A non-reflective frequency-sensitive phase shift element, connected between the couplers in one waveguide, produces a lag of 180 degrees for signals of one frequency and zero lag for the other. In the second waveguide an adjustable piston is fitted for equalizing the path lengths in the two waveguides between the couplers. The phase shifter comprises a hybrid directional coupler having two conjugate pairs of arms and a pair of similar cavity resonators connected to one conjugate pair of arms. The resonant frequency of the cavities is selected midway between the diplexed frequencies and the cavities may be tunable to permit changing of the diplexing frequencies. An alternative form of phase shifter consists of a waveguide filter section having a varying phase shift as a function of frequency, such as an m-derived bandpass filter. Specification 817,569 is referred to.