Abstract: A transponder adapted to be carried on the body of a person for use in locating avalanche victims is designed for cooperation with a search-transmitter and includes a receiver having a passive non-linear element which, by distortion, produces a higher harmonic from the fundamental frequency received from the search-transmitter and includes metal parts which are connected to the non-linear element and function as a receiver/transmitter antenna tuned to the frequency employed, whereby the side of the transponder facing the human body is covered with a dielectric layer the thickness of which is adjusted in accordance with a transmitted frequency of 1000 MHz and in accordance with the dielectric constant of the layer, and whereby the size of the antenna is adjusted in accordance with the dielectric constant.

Abstract: A novel DME transponder having a plurality of directional antennas arranged equidistantly on a circle each having a radial, highly directional pattern and as a group covering 360.degree. in the azimuth plane. The antennas are divided into at least two groups of nonadjacent antennas. Each group is connected to a receiver. The DME reply signal is radiated from the group containing the antenna which has received the DME interrogation signal with the greatest amplitude. The signal radiated in the direction of the interrogator is the DME reply signal, and the signals radiated in the other directions are used as filler pulses.