Duplexer

What Does Duplexer Mean?

A duplexer is an essential component in modern gadgets using radio communications. It permits
duplex communications, which allows bidirectional transmission on a single
path. There are many different types of duplexers. An example of a duplexer
based on frequency is a wavelength filter, while a duplex based on polarization is an orthomode transducer. In radars, a duplexer based on timing
is used. Put simply, when a transmitter and a receiver use the same
antenna for communications, an electrical switch is used. This electronic
switching system is known as a duplexer. Without a duplexer, signal and
frequency interference between the transmitted frequency and the received
frequency can damage the receiver.

Techopedia Explains Duplexer

A duplexer
is very important for radio apparatus as it allows the switching of the pathway
of the signals toward either the transmitter or the receiver. A
duplexer a special type of electronic switch which can open or
close very quickly based on the type of signals it handles. In transceiver systems like radars, the transmitter and
the receiver often share the same circuitry and components, including the same
antenna. If the transmitter and the receiver use the antenna at the same
frequency, then the signal interference can almost immediately damage the
receiver’s components. This is highly undesirable, and so a system
had to be developed which would allow the switching between transmitting or
receiving modes in the short spans of time between transmitting and receiving. An
easy solution for this is a switch that can transfer the signals and switch the
pathways quickly with respect to specific transmitted and echo pulses. However, it is not possible for simple mechanical switches
to operate so quickly, so electrical switches known as duplexers must be used.