Keysight / Agilent / HP 11940A Close-Field Probe

The Keysight/Agilent/HP 11940A is a handheld near-field probe engineered for identifying and characterizing sources of radiated electromagnetic interference (EMI) at the component and circuit board level. Operating from 30 Hz to 100 kHz, this legacy probe enables precise localization of EMI sources through close-field measurement, making it essential for pre-compliance testing and root cause analysis of electronic device failures.

Technical Specifications

Frequency Range: 30 Hz to 100 kHz

Probe Type: Near-field probe

Connector: BNC

Impedance: Optimized for standard spectrum analyzer and EMI receiver input impedances

Key Features

Detects low-level emissions for identification of subtle EMI sources

Flexible cable design for maneuverability across device surfaces

Handheld form factor suited for laboratory and field environments

Durable construction for sustained operational use

Typical Applications

Pre-compliance EMI testing prior to formal certification

Troubleshooting electronic products exhibiting EMI problems

Characterizing emission signatures from specific components and circuit traces

Design debugging to minimize radiated emissions

Compatibility & Integration The 11940A interfaces directly with spectrum analyzers and EMI receivers. Measurement is performed by sweeping the probe across the surface under test; the probe's output displays areas of high emission when connected to a spectrum analyzer. The probe works with effective signal transfer with typical test equipment input impedances.