NOTICE: Due to a lapse in annual appropriations, most of this website is not being updated. Learn more.

Form submissions will still be accepted but will not receive responses at this time. Sections of this site for programs using non-appropriated funds (such as NVLAP) or those that are excepted from the shutdown (such as CHIPS and NVD) will continue to be updated.

U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Advancing Power Metrology at NIST CTL

Delivering Precision in Radio Frequency (RF) Measurements

Share

Microcalorimeter
Credit: CTL

In today's commerce and technology, accurate and standardized measurements are foundational. From global telecommunications to defense systems, consistent electrical measurements ensure components developed in different parts of the world work seamlessly together. At the heart of this measurement infrastructure is the National Institute of Standards and Technology Communications Technology Laboratory (NIST CTL) which plays a vital role in enabling traceability and precision in radio-frequency (RF) power metrology across the Department of Defense (DOD), industry, and other government agencies. 

The Need for Traceability 

Traceability is defined as the “property of a measurement result whereby the result can be related to a reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty.”  This reference is ultimately the fundamental constants of nature that define the International System of Units (SI). 

In RF power metrology, traceability facilitates global commerce by standardizing measurements across international borders. For example, a power sensor manufactured in the United States provides the same reading as one produced in Germany, because both are calibrated against a universally agreed-upon standard—the watt. Achieving such consistency requires high-precision calibration techniques and standards, which NIST CTL provides. 

Foundations of RF Power Measurements 

At NIST CTL, RF power measurements are traceable to direct current (DC) power, calculated from voltage and resistance. Both voltage and resistance are measurable with exceptional accuracy thanks to quantum standards such as the Josephson voltage standard and the quantum Hall resistance standard. 

The comparison between RF and DC power is performed using a sophisticated instrument known as a microcalorimeter. This device measures the effective efficiency of bolometric or thermoelectric power sensors that absorb both DC and RF energy. These sensors generate heat proportional to the power absorbed, and this heat is detected via thermopiles. By supplying DC power to the power sensor, it is possible to calibrate the thermopile so that it can be used to measure RF power absorbed in the sensor.  

Reducing Uncertainty through Modeling 

Measurement uncertainty is the doubt about the true value of the measurand that remains after making a measurement and is necessary for making informed decisions based on a measurement result. For instance, manufacturers often test the performance of components before sending them to customers. If a component fails a test, did it fail because the component was defective, or because of the accuracy of the measurement equipment? 

Part of the role of NIST is to help stakeholders understand and reduce this doubt. One of the ways NIST does this is by providing measurement results with low, and well-characterized uncertainties through measurement services. Another way NIST helps stakeholders reduce measurement uncertainty is through developing and publishing measurement techniques. To support these activities, NIST CTL researchers invest substantial effort in constructing detailed thermal and electromagnetic models of their measurement systems to refine uncertainty estimates.  

Serving the Nation: DoD and Industry Clients 

The primary clients for NIST CTL for RF power calibration services include Department of Defense (DoD) calibration laboratories and leading instrument manufacturers. These clients depend on NIST-calibrated devices to establish their own traceability chains.  

DoD labs, such as the Navy Primary Standards Lab and the Army Primary Standards Lab, use devices calibrated by NIST to verify performance of mission-critical field equipment. Similarly, commercial instrument manufacturers use NIST traceability to validate their systems, ensuring the reliability of the tools their customers rely on. 

Key Projects and Innovations 

NIST is actively deploying microcalorimeter systems compatible with 2.4 mm coaxial connectors, supporting frequencies up to 50 GHz, to the Navy Primary Standards Laboratory and the Army Primary Standards Laboratory. These systems enable these labs to perform their own high-precision, traceable RF power calibrations, increasing autonomy and resilience in critical calibration infrastructure. 

To complement microcalorimeters, NIST is also delivering direct comparison systems to the Navy. These systems facilitate efficient transfer of calibrations from primary standards to customer devices, ensuring the precision of working standards used in day-to-day operations. 

Semiconductor manufacturing processes, such as plasma etching and deposition, rely on high-power RF systems. NIST is developing techniques to perform scattering parameter, phase, and RF power measurements up to 5 kW. These capabilities aim to make semiconductor processes more reproducible, potentially boosting production yields. 

In response to increasing demand from the telecommunications sector, NIST is developing traceable on-wafer RF power and scattering parameter measurements. These methods enable precision testing of integrated circuit components—such as amplifiers, mixers, and filters—before they are embedded in communication devices like smartphones and base stations. 

Recognizing the growing complexity of RF systems, NIST is developing sophisticated uncertainty analysis software for broader distribution. These tools empower engineers across DoD, industry, and academia to better understand and minimize measurement uncertainty in their own laboratories. 

NIST CTL is working to extend its RF metrology infrastructure to higher frequencies, with active development in the WR-6 waveguide band (110 GHz to 170 GHz). Long-term, the goal is to provide traceability up to 1 terahertz (THz), supporting the next generation of ultra-high-frequency applications, including 6G and beyond. 

Power metrology at NIST CTL is not just about measuring watts—it’s about enabling trust, reliability, and performance in the technologies that define our digital and defense infrastructure. Through rigorous science, advanced instrumentation, and close collaboration with industry and government partners, NIST CTL continues to set the standard in RF measurement science. 

To learn more about the NIST CTL power metrology services please contact Dr. Chris Long at christian.long [at] nist.gov (christian[dot]long[at]nist[dot]gov) or (303) 497-6559. 

Advanced communications
Released August 7, 2025
Was this page helpful?