Characterization and Detection of RF Electronics Using Localized Conjugate Component

Nonlinear radar has a unique advantage in finding nonlinear targets, like radio frequency (RF) electronics and harmonic tags, under clutter circumstances, among which intermodulation-based schemes are usually favored for their resistance to self-harmonics interference. Currently, intermodulations produced by multiple large signals are dominantly used for nonlinear target characterization and detection. However, this article proposes to exploit the intermodulation generated by the large and small signals, referred to as localized conjugate component (LCC). We observe that the LCC describes the localized nonlinear structure, which contains discriminative representation exclusive to nonlinear targets. Compared with traditional intermodulation detection, LCC is independent of the small signal's waveform and dependent on the power-dependent scattering parameter, which makes it flexible for waveform design and cost effective for performance estimation. Benchtop measurement results validate the aforementioned properties. Furthermore, an over-the-air experiment confirms the feasibility of nonlinear target detection at a stand-off distance using LCC. Its application prospects in target identification are also presented.