52 to the voice operated switch 53 if no voice signal is present at the output of the amplifier 52 the voice operated switch 53 de energizes the oscillator 55 and amplifier 56 one potential problem of the use of dipoles in electronic short range communication systems is that at certain orientations the field may be perpendicular to the dipole axis and if another dipole is displaced from the first dipole in this direction and with its axis parallel to the axis of the first dipole the second dipole will not have any signal induced into it by the first dipole in other words the two dipoles will be uncoupled in certain relative orientations and there will be a null in the received signal under these conditions if only single dipoles are used at the transmitter and receiver there will be locations and orientations between the dipoles which will produce a null this problem can be solved by providing either receiving or transmitting portions of each unit of the system with three noncoplanar dipoles and suitable provision for coupling to them three noncoplanar dipoles cannot be in a null condition at the same time fig1 illustrates a receiver having three noncoplanar receiving dipoles for use with a transmitter such.