Manufacturers : RF and microwave electronics : Diplexers

A diplexer is a device which separates a received signal into two frequency ranges within the received signal. Diplexers split an incoming signal into two component parts, respectively having differing frequency components. A diplexer couples the feed structure to transceivers operating at the different frequencies. Diplexers can separate incoming signals at the two frequency bands, and can couple outgoing signals at the two frequency bands to a common feed of the antenna. Satellite communication systems conventionally employ orthogonally polarized signals for effecting two-way communications over the same channel. Satellites in earth orbit frequently utilize the same antenna for both transmitting and receiving signals from earth. The frequencies of the transmit signal and the received signal are usually different in such a case to avoid interference between signals. A diplexer is typically used in a satellite dish antenna to separate the transmit and receive frequencies so that the transmit channel does not overpower or saturate the receive channel. The frequency splitting properties of diplexers are often used in the communications field, and particularly in radars to switch between two different operating frequencies. Polarization diplexer devices are generally used in microwave devices in which two waves with orthogonal polarizations must propagate in the same wave guide. The diplexer is usually constructed with tuned elements in both the through and the side channels to form filters in these channels so that each of these two channels propagates radiation at only one of the two frequency bands while inhibiting propagation at the other of the frequencies. Conventional diplexers comprise discrete circuit components to bandpass, highpass or lowpass filter a received signal into two frequency ranges. Diplexers are either fixed tuned or tunable over a range of transmit/receive frequencies by tuning the filter's resonators and adjusting its couplings.

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