Junction range finder

An apparatus is described for locating an electrically nonlinear object and determining the distance to the object by transmitting an FM signal in the vicinity of the nonlinear object causing a signal of a higher harmonic to be reflected by the nonlinear object. A receiver is provided for receiving the higher harmonic reflected signal. It is compared with the initial exciting signal so as to produce a signal, the amplitude of which is directly proportional to the distance to the object.