Manufacturers : RF and microwave electronics : Duplexer

A duplexer is used in a communications device to pass transmission signals and received signals in different frequency bands. A duplexer isolates the transmitter and the receiver to permit simultaneous operation in duplex operation of a radio transmitter and a receiver connected to a common antenna. Duplexers are usually devices found at the end of a system in items of radio equipment. They are designed to separate the signals transmitted from the signals received by the antenna. In communication systems that employ a common antenna for use with a transmitter unit and a receiver unit, a duplexer interlinks the transmitter unit, the receiver unit, and the common antenna. A duplexer is used to couple the common signal path to the input of the receiver and to the output of the transmitter. The duplexer provides the necessary coupling while preventing the modulated transmit signal generated by the transmitter from being coupled from the antenna back to the input of the receiver and overloading the receiver. There are some types of antenna duplexers used in communication terminal equipment. A monoblock dielectric duplexer comprises a block of a dielectric material. The monoblock dielectric duplexer typically comprises a transmit-filtering portion and a receive-filtering portion, wherein the frequency band of the transmit-filtering portion relatively is lower than that of the receive-filtering portion. A dielectric type duplexer uses a dielectric for transmit and receive filters. A typical duplexer is a combination of bandpass and band-reject filters that allow signals from the transmitter to reach the antenna while preventing the transmit signals from reaching the receiver.