This application note describes the different types of switch matrix products available for IF, RF and microwave switching. It also discusses many of the important tradeoffs that should be considered when selecting a switch matrix to fit your application.
Many installations and facilities use switch matrix products throughout the entire signal chain. This paper is focused on those portions of the system where the signals being switched are (typically) modulated carriers. The type of modulation is not important to our discussion, since the switch matrix only has to pass the signal without degrading it. We are interested in the portions of systems passing RF signals that are already modulated (on the transmit side) or not yet demodulated on the receive side. Signals received from an antenna or down-converted by a LNB, for instance, are part of our discussion. So are multiple carrier multiplexes being prepared for transmission.
But we exclude switches designed for baseband or digital signals such as RS-232, ECL, RGB video, audio and similar signals. Although some of these signal types can cover many MHz of bandwidth, they require switch matrix designs that are substantially different than those of an RF, IF or microwave switch.
For the purposes of this paper, we will assume that the application is a satellite communication ground station. The process of selecting a switch can be applied equally well to other application areas, but it is convenient to use one of the most common applications, because it provides a variety of possible switching configurations for our discussion.
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