monostatic

Monostatic is a term used in radar, sonar, and other sensing disciplines to describe a configuration in which the transmitter and receiver are located at the same place. In most cases a single antenna is used and switched between transmit and receive using a duplexer, though two physically co-located antennas may also serve as monostatic elements. This contrasts with bistatic systems, where the transmitter and receiver are at separate locations, and multistatic systems with multiple transmitters and/or receivers.

In operation, the system emits a pulse or continuous wave signal, which propagates, reflects from targets, and is detected by the same site. Range is determined from the time delay, while Doppler processing yields velocity information. Monostatic geometries simplify deployment, maximize energy efficiency at the target, and generally provide straightforward geometry for target localization and beam steering, especially when using electronically scanned or phased-array antennas. However, the transmitter's strong out-of-band signal and the receive path's isolation requirements create design challenges, including the need for fast, reliable isolation between transmit and receive channels and avoidance of self-interference.

Applications include air and weather surveillance radars, automotive radars for collision avoidance, and many ground- and space-based sensing systems. In sonar and medical ultrasound, monostatic configurations describe transducers that both transmit and receive at the same location, with similar advantages and constraints. Related terms include bistatic and multistatic radar, which place one or more receivers and transmitters at separate locations, extending coverage and geometry but increasing system complexity.