Waveguide Microwave Power Micro-Calorimeters
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Waveguide micro-calorimeters are used by Primary Metrology Laboratories to underpin world leading measurements of microwave power.
Application
Micro-calorimeters, and the associated measurement systems, are used to deliver world leading measurements of the efficiency of waveguide power sensors. They are normally intended to operate with commercially manufactured thermistor mount sensors, but can in principle be adapted for use with any ‘thermal substitution’ microwave power sensor. They are slow in operation and therefore are commonly used to calibrate local transfer standards which are then used with transfer instruments to calibrate other power sensors. Typically the calorimeter will operate at a power level of 1 to 10 mW, but this is dependant on the sensor being calibrated.
Frequency Coverage
NPL operates waveguide calorimeters in multiple waveguide sizes from 8.2 to 110 GHz, but we have built one device capable of operating up to 170 GHz. Since these are bespoke instruments they can be built to operate in most commercial waveguide bands.
Associated Equipment
NPL is able to deliver a complete power measurement facility, including the calorimeter, microwave source, drive system, measurement and analysis software and documentation. Training and on site installation can be supplied if required. As temperature stability is important to the quality of the measurement it is usual to operate the system in a temperature controlled laboratory and house the calorimeter itself in either a water or air bath.
Related Standards
For coaxial applications we can supply coaxial calorimeters and transfer systems.
Measurement Uncertainties
The calorimeters, being developed from our own standards, offer the user comparable measurement uncertainties to that available from NPL’s measurement service. Our capabilities have been verified and accredited by the United Kingdom Accreditation Service (UKAS) and our capability can be found on their website and also on the BIPM Calibration and Measurement Capability database.