Difference between Diplexer & Duplexer

"Difference between Diplexer & Duplexer"

Diplexer => Diplexer separates two different frequency bands in receive path and combines them in transmit path. These frequency bands usually will be wide apart in frequency domain for diplexer to work satisfactorily.
It is often referred as RF power combiner/divider with added functionality of filtering. Broadband Filters are used to pass appropriate bands at Tx and Rx path.

Examples => Diplexer is used to separate/combine frequency bands of GSM 900 and DCS 1800 systems. It is also used in multiband design of mobile handset with multiple technologies GSM, CDMA, LTE.
As shown inthe figure, diplexer does multiplexing and demultiplexing of wide frequency bands with much appropriate difference. Figure shows L and H bands at S port.

Duplexer => A Duplexer is a device that allows use of the single antenna by both transmitter and receiver. In other words duplexer is a device which couples the transmitter and receiver to the antenna while producing isolation between transmitter and receiver.

There are two types of duplexer, one by using PIN diode switches and the other using circulators as shown. Both transmit and receive paths usually will have frequency bands very nearer, hence narrow band filters are used to separate these frequencies. Duplexer is often referred as 3-port RF circulator.

Example => It separates Uplink (890-915MHz,Uplink-UL) and Downlink (935-960MHz,Downlink-DL) frequency bands in GSM900 system.