Electromagnetic compatibility aspects of impulse radars

It is noted that impulse radars are characterized by extremely short pulses; these can be of the order of one or two RF cycles long. However, it has been shown that a half-wave dipole excited by a short pulse produces a field with an additional half cycle at the beginning and end of the applied pulse. These half cycles have an amplitude one half that of the rest of the pulse. A model of the spectrum resulting from exciting a half-wave dipole with a pulse one cycle long, together with estimates of the gain of an array of dipoles, is used together with a space attenuation model and receiver models, to determine the distance separation needed to keep the undesired signal in the receiver below its detection threshold. Alternatives for the case where distance separation cannot preclude interference are discussed. Typical examples of distance separation between a theoretical model of an impulse radar and receivers onboard US Navy ships, such as VLF, HF, and VHF communications, other radars, and IFF receivers, in various portions of the spectrum are illustrated