RF EMF Strength Meter Extech offers the RF EMF Strength Meter for high frequency measurement in the 50MHz to 3.5GHz range. The Extech RF EMF Strength Meter features non-directional (isotropic) measurement with a three-channel (triaxial) measurement probe, max hold and average functions, manual store and recall up to 99 sets, and level exceed audible alarm with user selectable threshold. Ideal for electromagnetic field strength measurement including mobile phones, cell phones, base stations, and microwave leakage.