Nonlinear Characterization and Detection Using Simultaneous Multipower-Scale Excitation

Nonlinear radar has garnered significant attention in recent years due to its unique advantage in detecting man-made electronics under strong clutter conditions. Currently, nonlinear radars primarily rely on harmonic and intermodulation (IM) signatures, where the generation of new frequency components is the defining feature of nonlinear scattering. However, this work breaks ground by exploiting the discrepancies of power-dependent response as an alternative nonlinear characterization and detection paradigm. We propose simultaneous multipower-scale excitation (SMPSE), which integrates large and small signals to concurrently capture scattering characteristics across different power levels. The intrinsic constraint relationships (ICRs) between the power-dependent scattering parameters and IM efficiency are further revealed, which is validated by the measured data of typical RF front-end targets. Furthermore, a stepped-SMPSE methodology for nonlinear detection is proposed based on ICRs, which successfully achieves simultaneous linear and nonlinear range profile estimation with 4-GHz bandwidth in over-the-air (OTA) experiments. The proposed method holds great potential for precise diagnostic localization of nonlinear nodes and novel radar systems simultaneously integrating linear and nonlinear signatures.