The Keysight (Agilent) 11945A is a close-field probe set designed for electromagnetic compatibility (EMC) measurements and troubleshooting over the 9 kHz to 1 GHz frequency range. It contains two passive, dual-loop magnetic-field (H-field) probes, the 11940A and 11941A, each optimized for specific frequency bands and individually calibrated for high precision. The probes feature exceptional electric-field (E-field) rejection and have their unique calibration factors conveniently plotted directly onto each probe body.

Specifications

Physical

ParameterValue
Operating Temperature0 °C to +55 °C
Dimensions (W×H×D)279 mm × 102 mm × 337 mm (carrying case)
Weight1.4 kg
Shipping Weight2.3 kg
Option E51 Net Weight3.5 kg
Option E51 Shipping Weight4.5 kg

System Performance

ParameterValue
Combined Frequency Range9 kHz to 1 GHz

Kit Contents

ParameterValue
Included Probe Models11940A (30 MHz to 1 GHz), 11941A (9 kHz to 30 MHz)
Probe 1 Model11940A
Probe 2 Model11941A
Included Carrying CaseYes (hard carrying case with custom foam insert)

11940A Specifications

ParameterValue
Probe 1 Frequency Range30 MHz to 1 GHz
Probe 1 Maximum RF Input Power0.5 W
Probe 1 Output Impedance50 ohms (nominal)
Probe 1 Output ConnectorSMA (female)
Probe 1 CalibrationIndividually calibrated; calibration data plotted on probe body

11941A Specifications

ParameterValue
Probe 2 Frequency Range9 kHz to 30 MHz
Probe 2 Maximum RF Input Power0.5 W
Probe 2 Output Impedance50 ohms (nominal)
Probe 2 Output ConnectorSMA (female)
Probe 2 CalibrationIndividually calibrated; calibration data plotted on probe body

Design & Construction

ParameterValue
Probe Sensor DesignDual-loop shielded H-field (magnetic field) sensor
E-Field RejectionTypically > 30 dB

Calibration

ParameterValue
Calibration TraceabilityTraceable to US National Institute of Standards and Technology (NIST)

Environmental

ParameterValue
Storage Temperature-40 °C to +75 °C

Option E51 Preamplifier

ParameterValue
Option E51 Preamplifier Gain30 dB
Option E51 Preamplifier Frequency Range9 kHz to 1 GHz
Option E51 Preamplifier Part Number11945-60001
Option E51 Preamplifier Gain Flatness±1.5 dB
Option E51 Preamplifier Noise Figure< 7 dB
Option E51 Preamplifier Input ConnectorBNC female
Option E51 Preamplifier Output ConnectorBNC female
Option E51 Preamplifier Input Impedance50 Ω nominal
Option E51 Preamplifier Output Impedance50 Ω nominal
Option E51 Preamplifier DC Power Requirement15 Vdc, 120 mA

Option E51 Power Supply

ParameterValue
Option E51 Power Supply Input Voltage115 V AC / 230 V AC (option dependent, ±10%, 50/60 Hz)

Probe 1 (11940A)

ParameterValue
Probe 1 Length205 mm (8.1 in)
Probe 1 Tip Width19 mm (0.75 in)
Probe 1 Tip Thickness11 mm (0.43 in)
Probe 1 Maximum Safe Magnetic Field0.2 A/m
Probe 1 Calibration Accuracy±2 dB (in a 50 Ω system)

Probe 2 (11941A)

ParameterValue
Probe 2 Length205 mm (8.1 in)
Probe 2 Tip Width19 mm (0.75 in)
Probe 2 Tip Thickness11 mm (0.43 in)
Probe 2 Maximum Safe Magnetic Field15 A/m (9 kHz to 100 kHz), 1.6 A/m (100 kHz to 30 MHz)
Probe 2 Calibration Accuracy±2 dB (in a 50 Ω system)

Technology

EMC Near-Field Probing

Applications

Electromagnetic Interference (EMI) Diagnostics and Troubleshooting