Some notes on strip transmission line and waveguide multiplexers

This paper describes techniques which have been developed to facilitate the design of r-f multiplexers within the frequency range of 1.O to 15.0 kmc. By using techniques involving modern network synthesis, strip transmission line and waveguide filters which approximate Butter-worth or Tchebycheff functions can be easily realized. Strip transmission line filters are discussed which use tuning screws, physical variations of cavity lengths, and replaceable gaps. The waveguide filters consist of resonant cavities or resonant elements, depending on the application. Waveguide multiplexing is accomplished by using hybrid junctions, resulting in essentially no passband deterioration. An alternate technique utilizing a modified Fox type coupler in conjunction with a 3 db directional coupler is also presented. Strip transmission line 3 db directional couplers are used to multiplex the lower frequency bandpass filters.