Ultra-wideband (also known as UWB, ultra-wide band and ultraband) is a radio technology pioneered by Robert A. Scholtz and others which may be used at a very low energy level for short-range, high-bandwidth communications using a large portion of the radio spectrum. UWB has traditional applications in non-cooperative radar imaging. Most recent applications target sensor data collection, precision locating and tracking applications.

Similar to spread spectrum, UWB communications transmit in a way which does not interfere with conventional narrowband and carrier wave uses in the same frequency band. Unlike spread spectrum, however, ultra-wideband does not employ frequency-hopping (FHSS).

Ultra-wideband is a technology for transmitting information spread over a large bandwidth (>500 MHz); this should, in theory and under the right circumstances, be able to share spectrum with other users. Regulatory settings by the Federal Communications Commission (FCC) in the United States intend to provide an efficient use of radio bandwidth while enabling high-data-rate personal area network (PAN) wireless connectivity; longer-range, low-data-rate applications; and radar and imaging systems.