Diplexer

A diplexer is a device that combines radio frequency inputs from two or more radio transmitters into a single output, or, when used in the opposite direction, divides a single RF input into two or more outputs based on frequency using bandpass filters. Depending on how it is used, a diplexer may be called a combiner or splitter. The device is referred to as a duplexer in land mobile radio, where a receiver and transmitter are sometimes combined onto the same antenna. Though the basic goal is the same in all diplexers, there are massive variations in scale depending upon the application.
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A three-port frequency-dependent device that may be used as a separator or a combiner of signals. (188 ) Note: Duplex transmission through a diplexer is not possible.