A Station Monitor is a specialized measuring instrument for high frequency technology. Here, both the matching (impedance) of the antenna and the performance of the transmitter are monitored with high precision. By also accurately measuring the phase of the transmitted signal - something that normal SWR meters are not able to do - much more extensive measurement options are possible. For example, the influence of the cable to the antenna can be taken into account. Usually, separate sensors are inserted into the antenna cable to operate a station monitor. This allows the display unit of the monitor to be conveniently positioned near the operating station.