A Resonant E-Field Probe for RFI Measurements

Near-field probes with high sensitivity facilitate the identification of the root causes of intrasystem radio frequency interference issues, where weak noise desensitizes the receiver. In the study presented in this paper, a high-sensitivity resonant electric field probe was designed, consisting of an LC resonator loaded by quarter-wave transformers for optimal power transfer at the resonant frequency. Based on the equivalent circuit model, analytical derivations and numerical simulations were performed to illustrate the design methodology. The simulation results agreed well with the measured values. At the resonant frequency of 1.577 GHz, the measured |S₂₁| from a matched trace to the resonant probe was approximately 6.6 dB higher than that of an equivalently sized broadband probe.