OK, that thing on the end of a metal detector rod that goes over the ground, what do we call it? Inside that shell there is a coil of wire, some might call it a loop of wire. So you tend to hear two terms. White's Electronics liked calling them "loops" for many years but now most companies refer to them as "search coils" or simply "coils". Search coils are nothing more than an antenna built to both transmit and receive a signal. As such they are usually tuned to work on specific detectors a