What device converts the RF input and output of a transceiver to another band?

A transverter (a combination of the words "transmitter" and "converter") is a piece of equipment that attaches to a transceiver to change its operating frequency to a completely different band. It works in both directions, shifting the transmitted signal to the new band and converting incoming signals from the new band back to the transceiver's original receiving frequency. High-pass and low-pass filters only allow certain frequencies to pass through while blocking others; they cannot shift or convert signals to new frequency bands. A phase converter alters the phase of an alternating current supply, which is used in electrical power applications rather than RF band conversion.