Agilent 11940A / 11941A Close-Field probe 30MHz-1GHz

The Agilent 11940A and 11941A Close-Field Probes are magnetic field detection instruments designed for EMC diagnostic and troubleshooting of electronic components, circuit boards, slots, and cables. These probes deliver high spatial resolution with exceptional electric field rejection, identify interference sources early in product development and obtain calibrated, repeatable measurements across their respective frequency bands.

Technical Specifications

• Frequency Range: 30 MHz – 1 GHz


• Maximum Input Power: 0.5 W


• Dielectric Breakdown: ±1 kV (typical)


• Connector Type: SMA, replaceable barrel


• VSWR: < 3:1 (typical)


• Antenna Factor Accuracy: ±2 dB (377 Ω field impedance)


• Operating Temperature: 0 °C to +40 °C Agilent 11941A


• Frequency Range: 9 kHz – 30 MHz


• Maximum Input Power: 0.5 W


• Dielectric Breakdown: ±1 kV (typical)


• Connector Type: SMA, replaceable barrel


• Antenna Factor Accuracy: ±2 dB (377 Ω field impedance)


• Operating Temperature: 0 °C to +40 °C

Key Features

• Individual factory calibration ensures measurement accuracy and repeatability


• High electric field rejection minimizes unwanted coupling during close-field measurements


• Replaceable SMA barrel connectors support field maintenance


• Low VSWR performance maintains signal integrity across operating frequencies

Typical Applications

• Magnetic field radiation measurement from surface currents, slots, cables, and integrated circuits


• EMC pre-compliance and diagnostic troubleshooting


• Interference source identification during design validation


• Near-field analysis in product development cycles

Compatibility & Integration Each probe ships with 2 meters of RG-223 coaxial cable, SMA(f) to Type-N(m) adapter, and SMA(f) to BNC(m) adapter. The Agilent 11945A Close Field Probe Set combines both models, providing continuous frequency coverage from 9 kHz to 1 GHz for comprehensive near-field characterization.