Field Strength, Frequency & Modulation
The field strength (3–10 V/m), the frequency sweep (80 MHz–6 GHz), and the 80% AM modulation that makes RF demodulate inside your circuits.
Severity is a field strength in volts per metre. Common levels are 3 V/m (residential/commercial), 10 V/m (industrial), and higher for automotive, medical life-support, or military. The field is established and calibrated without the EUT (field uniformity), then the EUT is placed in that known field.
The classic sweep is 80 MHz–1 GHz, extended to 2.7 / 6 GHz in later editions to cover cellular and Wi-Fi. The field is swept slowly with a defined dwell so every frequency is exercised. Because coupling is resonant, a cable is most susceptible when its length is near a multiple of λ/4 — use the calculator to see where.
The carrier is amplitude-modulated 80% at 1 kHz. This is the crucial detail: a pure carrier often does nothing, but once it is demodulated at a nonlinear junction inside the product, the 1 kHz envelope appears as a real in-band disturbance on a sensor or audio line. Modulation is what turns invisible RF into a measurable malfunction.