Stimulating Carrier Modulation From Electronics Using A Transverse Electromagnetic Cell

Intermodulation radar is an established technique for locating electromagnetically-nonlinear junctions. For this type of radar, the probe consists of multiple simultaneous frequencies, usually two tones of equal amplitude. The multiple frequencies illuminate the target, mix with each other, and generate integer sums and differences of the original transmitted tones.This work studies a variation on the intermodulation-radar technique. Some targets, such as AM/FM transmitters, emit radio frequencies without being actively probed; thus, some collections of (powered) nonlinear junctions generate at least one internal tone which might be mixed with an externally-applied probe tone. This internal-external mixing is referred to as "carrier modulation," where the carrier is associated with the target and its modulation is induced by the transmit probe.This paper documents an experiment conducted using a transverse electromagnetic cell: contactless excitation of carrier modulation from active nonlinear junctions. Data recorded from two radio transmitters indicate that, for this internal-external mixing technique, a reduction in transmit power results in less of a reduction in received power compared to traditional intermodulation radar.