Coaxial cavity filters for multiplexing of 900-megacycle radio relay systems

Band-pass filters have been developed to provide for simultaneous application to a single antenna of two or more radio transmitters and/or receivers operating in the 900-megacycle (mc) range. By multiplexing transmitters or multiplexing receivers, or by diplexing a transmitter and receiver, considerable saving can be realized in equipment cost for multichannel radio systems. Filters consist of one or more sections of coaxial transmission line in tandem, adjusted for the desired degree of selectivity. In addition, filters are used to provide preselection and harmonic suppression where separate antennas are used for each transmitter and receiver.