Cavity diplexers are three port devices used in Tranceivers (transmitter and receiver) to separate the Transmitter frequency band from the receiver frequency band. They share a common antenna while working simultaneously at different frequencies. A diplexer is basically a high and a low pass filter connected to an antenna.
The transmitter part of the diplexer is different from the receiver in function its function is to filter out the transmitter sidebands that are generated ensuring the transmitter radiates within its allotted spectrum band and does not spill into adjacent frequency allocations. The receiver part of the diplexer is to protect the receiver from the overload on the transmitter. Diplexers are used on all duplex tranceivers covering all bands from high frequency to milliwave.
For example in a wireless communication system. The diplexer is to receive the passband of 1710 MHz to 1785 MHz and a to transmit the passband of 1805 MHz to 1880 MHz. Providing the unusual passband and notch responses for the overcrowded mobile sites.
Applications: One of the applications of the diplexer is to connect the dual band mobile radio’s two antenna connection to a common feed line.
Raditek makes cavity diplexers from 30MHz to 60GHz in power ranges from milliwatts to kilowatts