Nature presents examples of active sensing which are unique, sophisticated and incredibly fascinating. There are animals that sense the environment actively, for example through echolocation, which have evolved their capabilities over millions of years and that, as a result of evolution, have developed unique in-built sensing mechanisms that are often the envy of synthetic systems. This book presents some of the recent work that has been carried out to investigate how sophisticated sensing techniques used in nature can be applied to radar and sonar systems to improve their performance. Topics covered include biosonar inspired signal processing and acoustic imaging from echolocating bats; enhanced range resolution: comparison with the matched filter; air-coupled sonar systems inspired by bat echolocation; analysis of acoustic echoes from bat-pollinated plants; the biosonar arms race between bats and insects; biologically inspired coordination of guidance and adaptive radiated waveform for interception and rendezvous problems; cognitive sensor/ processor system framework for target tracking; the biosonar of the Mediterranean bottlenose dolphins; human echolocation; and polarization tensors and object recognition in weakly electric fish. Biologically-Inspired Radar and Sonar is essential reading for radar and sonar practitioners in academia and research, governmental and industrial organisations, engineers working in signal processing and sensing, and those with an underlying interest in the interaction between natural sciences and engineering.