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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.  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.