The Keysight FieldFox is a family of ruggedized, lightweight, battery-powered handheld analyzers built to withstand tough working conditions while making measurements on RF devices such as cables, antennas, filters, amplifiers, and for signal and spectrum analysis. The platform is configurable: by selecting FieldFox options and features, a single unit can be set up to address Cable and Antenna Test (CAT), Spectrum Analysis (SA), or Vector Network Analysis (VNA), along with real-time spectrum analysis and over-the-air digital demodulation. The C-Series, and the N9912C in particular, make FieldFox a truly software-defined instrument, while the newer D-Series expands IQ data streaming bandwidth up to 120 MHz and uses a Linux operating system to enhance instrument security.

FieldFox is positioned as a field-testing and deployment tool for modern wireless and microwave work. The datasheet describes it as an ideal 5G deployment and field-testing tool, capable of true RF coverage measurements up to 54 GHz and beyond, beamforming verification with phased array antenna support, and over-the-air measurements. It is also applied to radar and electronic warfare (EW) systems diagnostics, combining spectrum analysis, full 2-port VNA, power meter, pulse, and noise figure measurements, with results that correlate with high-performance benchtop instruments. Additional described uses include simplified field signal monitoring through wideband capture and recording of fully corrected IQ data, and characterization of cable and antenna systems on microwave links.

ValueTronics stocks and holds its own inventory in a 20,000 square foot secure warehouse at 1675 Cambridge Drive in Elgin, Illinois, so the instruments we list are equipment we keep on hand rather than source on demand. That combination lets buyers source FieldFox analyzers with confidence in both condition and availability.

Brand Heritage

Keysight Technologies traces its roots to Hewlett-Packard's test and measurement business, which was spun out as Agilent Technologies in 1999 and then established as Keysight Technologies in 2014. The Keysight, Agilent, and HP names all reflect stages of this same measurement-instrument lineage.

Compare Other Models in This Series

The FieldFox Handheld Analyzers span a broad family of models across the 4, 6.5, 9/10, 14, 18, 26.5, 32, 44, 50, and 54 GHz frequency points, offered in B-Series, C-Series, and D-Series variants. The family divides into two broad configuration paths: microwave combination analyzers, whose base is a Vector Network Analyzer and Cable and Antenna Analyzer, and signal analyzers, whose base is a Spectrum Analyzer. From those bases, each unit is built up with selectable options and field-upgradeable software license keys to match the application.

Across the series, the analyzers share a common ruggedized, battery-powered handheld design with a 6.5-inch anti-glare display, backlit keypad, and sealed enclosure rated to military and ingress-protection standards. The differences between individual models are primarily a matter of frequency coverage, series generation, and which measurement options are installed, as detailed in the comparison table below.

Each model in the FieldFox family below links to its own dedicated product page with condition-matched pricing. Selecting a new unit takes you to the listing for that specific model and frequency tier, where the configuration and available options for that new analyzer are presented.

The clearest difference across the family is frequency coverage, which ranges from 4 GHz at the low end up to 54 GHz at the top of the series, with intermediate models at 6.5, 9/10, 14, 18, 26.5, 32, 44, and 50 GHz. The maximum frequency of the N9912C can be configured to 4, 6.5, or 10 GHz at purchase and upgraded to a higher frequency by software license, reflecting the software-defined approach of the C-Series. Combination analyzer models and spectrum analyzer models also differ in which option set applies, since CAT, VNA, and SA capabilities are tied to different base configurations and option codes.

The series generation also distinguishes the models. The newly introduced D-Series expands IQ data streaming bandwidth up to 120 MHz, uses a Linux operating system for enhanced instrument security, adds high-speed SFP+ interfaces compliant with the 10 GbE standard, and provides a full-range DC power supply, whereas the B- and C-Series provide a variable-voltage DC bias source. Refer to the comparison table that follows for the per-model frequency and configuration details.

Additional differences in specifications beyond the few shown above are not listed here — see each model's full specifications below.

Product Core & Specifications

Important: Input safety labels on the N991xC and N993xC models read: +25 dBm RF, 40 VDC Max.

Important: FieldFox's built-in DC bias / DC power supply can power external bias-tees, probes, and active devices and bias Tower-Mounted Amplifiers (TMA); bias tees are available separately and are not included.

Important: USB power sensor measurements (Options 208, 302, and 330) require a separately-ordered Keysight USB power sensor (USB peak power sensor for pulse measurements). The sensor is not included with the analyzer.

Important: EMF measurements (Option 358) require connectivity to an external antenna - the AGOS Advanced Technologies Triaxial Isotropic Antenna or Keysight 85572A - which is ordered separately.

Important: Direction-finding and interference-finding applications require a separately-ordered Keysight directional antenna: the 85574A directional antenna for transmitter hunting, or the single-channel 85573A DF antenna for the Angle of Arrival (AoA) technique.

Important: Extended Range Transmission Analysis (ERTA) and TDOA direction finding require multiple FieldFox analyzers (two for ERTA; three or four networked analyzers for TDOA).

Important: Cable and Antenna Test (CAT) is not available on the N993x/6xB; a subset of CAT measurements (return loss and VSWR) is available as Option 320. Option 320 is not available on C or D models.

Important: The N9912C main chassis must be configured with at least one option from the instrument groups (CA/NA/SA); do not pick two options from the same instrument group (footnote on page 13).

Recommended pairing: combine the FieldFox spectrum analyzer with the Keysight 85574A handheld directional antenna for RF Direction Finding and transmitter hunting when equipped with the interference finding (manual) option and GPS feature.

About this New unit

This is a brand-new, factory-sealed unit, supplied exactly as it arrives from the manufacturer and backed by the full manufacturer warranty. For the exact configuration, available options, included accessories, or current lead time for your application, our Test Architects can confirm the details before you order.

ValueTronics supplies both new and used test and measurement equipment. New units ship factory-sealed, exactly as received from the manufacturer; every used unit is inspected and functionally verified in-house at our 20,000 sq ft secure facility in Elgin, Illinois before it ships. Our Test Architects can help you select the condition, calibration, and configuration that fit your application.

Please review the Manufacturer's Data Sheet to verify published specifications. Feedback on this webpage is always welcome — please reach out to your Test Architect at any time for questions or concerns. Thank you, we truly appreciate you being our customer.