The Agilent 8493C is a precision coaxial fixed attenuator covering DC to 26.5 GHz with APC-3.5 connectors. It is part of a broader family that includes the 8491A/B (Type-N, to 12.4 or 18 GHz) and 8493A/B (SMA, to 12.4 or 18 GHz). The 8493C is constructed using thin-film tantalum nitride deposited on a sapphire substrate, which is the design choice that enables its precision performance across the full specified band and resonance-free operation up to 34 GHz — the top frequency limit of the APC-3.5 connector itself.

The 8493C is used as a precision attenuation element wherever signal levels need controlled reduction at microwave frequencies. Documented applications include extending the range of sensitive power meters for higher-power measurements, padding poorly matched devices to improve overall system SWR, serving as a calibration standard in attenuation and RF substitution measurements, and reducing power levels delivered to sensitive components and instrumentation. The combination of low SWR, flat frequency response, and broad DC-to-26.5 GHz coverage makes the same unit suitable for both bench work and integration into measurement systems.

Brand Heritage

Agilent Technologies was spun off from Hewlett-Packard in 1999, taking the test & measurement and chemical analysis businesses with it. In 2014 the electronic measurement portion of Agilent was further divided, with the test & measurement product lines transferring to the newly formed Keysight Technologies; Agilent retained the life sciences and chemical analysis businesses. Instruments and accessories carrying the Agilent brand from that era are part of the same engineering lineage now continued under Keysight.

Compare Other Models in This Series

The 8491/8493 series spans three connector and frequency tiers from a single family of thin-film resistive-card coaxial attenuators. The 8491A/B uses Type-N connectors and covers DC to 12.4 GHz (8491A) or DC to 18 GHz (8491B), with attenuation values from 3 dB through 60 dB. The 8493A/B uses SMA connectors with the same frequency split and value range from 3 dB through 30 dB. The 8493C uses APC-3.5 connectors and extends coverage to 26.5 GHz, with attenuation values from 3 dB through 40 dB.

Across the family, the design principle is the same — a film-on-card resistive element backed by the connector type and material chosen for the band. The 8493C uses tantalum nitride on sapphire for its precision performance at microwave frequencies, while the 8491A/B and 8493A/B use the family's standard film construction matched to their respective Type-N and SMA connector systems.

Each model in the family is listed as its own product page with condition-matched pricing. Selecting the pre-owned 8493C versus a pre-owned 8491A or 8493A is a connector and frequency-coverage decision driven by the application, not a tier-up or tier-down within a single product line.

Within the family, the 8493C is the model to specify when the application requires APC-3.5 connectors and frequency coverage above 18 GHz. Its tantalum-nitride-on-sapphire construction is the specific design element that distinguishes it from the 8491 and 8493A/B units and that enables its specified performance through 26.5 GHz and its resonance-free behavior to 34 GHz.

The family differences fall along three axes printed in the datasheet: connector type (Type-N on 8491A/B, SMA on 8493A/B, APC-3.5 on 8493C), upper frequency limit (12.4 GHz on the A suffix, 18 GHz on the B suffix, 26.5 GHz on the C), and available attenuation values (8491A/B offers 3 through 60 dB; 8493A/B offers 3 through 30 dB; 8493C offers 3 through 40 dB). Maximum SWR also tightens as the model moves to higher frequencies and the APC-3.5 connector — the 8493C is specified at 1.10 from DC to 8 GHz versus 1.25 on the 8491A/8493A and 8491B/8493B Type-N and SMA variants over the same band.

The comparison table below lays out connector type, frequency coverage, available attenuation values, and SWR by band for each model in the family. Use it to match the model to the specific connector environment and upper frequency required by the measurement.

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

Accessories Supplied

• Four fixed coaxial attenuators (3, 6, 10, 20 dB) with 8491B values
• Calibration report certified traceable to the National Bureau of Standards
• Walnut accessory case

Product Core & Specifications

Attenuation Accuracy

SWR

Dimensions & Weight

About this used unit

• Warranty included
• Functional verification included
• Note that unnecessary accessories may not be included (contact Test Architect to confirm).

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.