A communicator is defined as a radio transmitter/receiver combination capable of operating off an internal power source; it is portable in the sense that it need not be connected to a power supply. It may transmit and receive voice, video, and data. Communicators 0.2 liters and under can be worn as earpieces, which are unnoticeable to the casual observer.
Communicators can be either broadcast or tight beam. Radio is the principal form of broadcast communications. Tight beam communicators are much more difficult to intercept or jam but are also somewhat more complex and require that the transmitter know the precise location of the receiver. Tight beam radio communicators require an antenna designed for focusing the transmission which adds both weight and cost.
The power of a radio communicator determines its effective broadcast range – the distance to which a clear signal will carry before it is sufficiently degraded to be indistinguishable from natural background noise and static.
All spacecraft, and many vehicles, are automatically equipped with radio receivers integral to their hulls. These allow reception of radio broadcasts. There are hand-held versions of these same receiver radio systems for personal use. In the event of these receivers being destroyed, the receiver arrays of many other types of electromagnetic sensors will function adequately as radio receivers.