The single stage transmitters have a shorter range and are used when the species is too small to carry a two-stage transmitter. A transmitter has an antenna which is either loop or whip. A whip antenna should be as long as possible to give maximum range, without interfering with the animal's behavior. In most applications, antenna are 150mm to 300mm long. The loop can form the collar for attaching to the animal.
Transmitters emit a pulsed signal at at rate that is set during manufacture.
The pulse rate and pulse width affect battery life. Sixty ppm is often preferred when tracking a large number of animals at frequent intervals. It runs on 1.5 volts which is usually supplied by any one of a large number of silver oxide or mercuric oxide batteries. The smallest packaged unit is designed to be glued to the animal and weighs 0.9 g. It will run for 15 days at 40 ppm.