Agilent/Keysight N9937A

The Keysight N9937A FieldFox is a handheld microwave spectrum analyzer engineered for RF and microwave field testing across 100 kHz to 18 GHz (5 kHz to 18 GHz alternate range). It delivers ± 0.5 dB amplitude accuracy without warm-up and captures intermittent signals with 10 MHz gap-free real-time bandwidth. Weighing 3.0 kg, the instrument suits field technicians and engineers requiring portable, accurate spectrum analysis.

The N9937A provides a dynamic range of 103 dB with spur-free dynamic range exceeding 105 dB. At 1 GHz, the displayed average noise level reaches -155 dBm, third-order intercept measures +15 dBm, and phase noise spans -111 dBc/Hz at 10 kHz offset to -113 dBc/Hz at 1 MHz offset. The built-in frequency reference maintains ±0.7 ppm accuracy with GPS lock capability.

Standard attenuation covers 30 dB in 5 dB steps. IF bandwidth selections range from 10 Hz to 100 kHz across nine options, with resolution points from 101 to 10,001 selectable. The instrument configures with dual built-in ports and supports spectrum analysis, power measurement, tracking generator, and independent signal source functions (30 kHz to 26.5 GHz).

Optional capabilities include radar pulse characterization, 5G/LTE over-the-air measurements, and I/Q data streaming at up to 1 MHz bandwidth. A 25 MHz IF output enables external digitization. GPS/GNSS integration provides geolocation and timestamping.

Output power reaches 1 dBm maximum; input impedance is 50 Ω. InstAlign delivers automatic internal amplitude alignment as environmental conditions change, maintaining ± 0.5 dB accuracy across spectrum analysis and power measurements.

Technical Specifications

• Frequency range: 100 kHz to 18 GHz (spectrum analyzer); 30 kHz to 26.5 GHz (independent signal source)


• Amplitude accuracy: ± 0.5 dB (spectrum analysis, power measurement, with InstAlign)


• DANL @ 1 GHz: -155 dBm


• Spur-free dynamic range: > 105 dB


• Dynamic range: 103 dB


• TOI @ 1 GHz: +15 dBm


• Phase noise @ 1 GHz: -111 dBc/Hz (10 kHz offset), -113 dBc/Hz (1 MHz offset)


• Real-time bandwidth: 10 MHz gap-free


• IF bandwidth: 10 Hz to 100 kHz (nine settings)


• Frequency reference: ±0.7 ppm (specification) with GPS lock; ±0.4 ppm typical


• Attenuation: 30 dB standard range, 5 dB steps


• Impedance: 50 Ω


• Output power: Up to 1 dBm


• Weight: 3.0 kg

Key Features

• Spectrum analysis with zero warm-up time


• Interference analysis including spectrogram and trace playback/recording


• Power measurement suite with built-in meter


• Tracking generator (configurable)


• Independent signal source (30 kHz to 26.5 GHz)


• I/Q data streaming (up to 1 MHz bandwidth)


• IF output for external digitization (25 MHz bandwidth)


• GPS/GNSS geolocation and timestamping


• Optional radar pulse and 5G/LTE OTA measurement modes


• InstAlign automatic amplitude correction

Typical Applications

• Field spectrum analysis and interference identification


• Radar pulse profiling and characterization


• 5G and LTE over-the-air measurements


• RF signal monitoring and I/Q capture


• Power meter functionality with USB sensor support


• Frequency domain analysis to 18 GHz

Compatibility & Integration Two built-in RF ports support simultaneous measurement configurations. USB sensor integration enables external power meter attachment. GPS/GNSS receiver provides synchronized timestamping for multi-site measurements.