Near-Field Probes

A simple antenna positioned right on your bench can reveal radiated emissions in real time. Learn how to separate product harmonics from ambient RF noise, track down capacitive and inductive coupling paths, and use copper tape and foil to hunt down leaky seams and apertures.

When cables become the culprit in radiated emissions failures, an RF current probe can catch what near-field probes miss. This installment of EMC Bench Notes walks through measurement technique, transfer impedance math, and a downloadable E-field calculator for pass/fail estimation.

An Arduino-based board with no solid ground return plane makes the perfect "what not to do" test case. Near-field probe measurements, spectrum analyzer captures, and real emissions data reveal why two-layer designs can be EMC trouble — and what it takes to fix them.

Near‑field probe techniques commonly used for EFT troubleshooting can also uncover radiated immunity failures. Using a real‑world audio device case study, this article shows how a simple benchtop setup exposed PCB‑level resonance, guided a low‑cost fix, and helped resolve chamber test failures.