Waveform-synthesis method that reduces battery power in an electrically small wideband radiating system

An electrically small antenna is extremely inefficient when operating over a large (multi-octave) bandwidth in a conventional radiating system. As a result, a large amount of prime battery power would be needed to generate sufficient radio frequency (RF) signal power to overcome the poor antenna efficiency and to induce the desired amount of radiation. An alternative method is described in which electronic switches are integrated within a small loop antenna. The switches operate at a rate greater than the RF carrier frequency and are used to synthesise the desired RF current waveform that passes through the loop. This switching circuit replaces the power amplifier in a conventional radiating system. The battery power needed to stimulate a given radiated signal strength is significantly less [a factor of 1/10 at very high frequency (VHF)] compared with the traditional wideband power amplifier/antenna system. The performance of a prototype VHF system is described.