AN OBJECT DETECTOR

An object detector comprising: a transmitter arranged to generate a transmit signal; a transmit loop antenna, coupled to said transmitter and arranged to radiate said transmit signal; and a receive loop antenna arranged to generate a receive signal from received radio waves; wherein said received radio waves include said radiated transmit signal and, in the presence of objects within range of the device which reradiate said transmit signal, one or more radio waves reradiated by such objects; said receive signal includes a component corresponding to said transmit signal and, in the presence of reradiated radio waves, one or more components corresponding to said reradiated radio waves; and said object detector further comprises a signal detector, coupled to said receive loop antenna and said transmitter, the signal detector arranged to detect changes in the amplitude and/or phase of said receive signal which are due to changes in said components corresponding to said reradiated radio waves.