Power sensor characterization from 110 GHz to 170 GHz using a waveguide calorimeter

This paper proposes a new calorimetry-based measurement method to measure absolute microwave power obtained through DC substituted power from 110 GHz to 170 GHz (WG 29, WR 6/7 or D-band) using a custom-designed thin film microwave power sensor. This method complements traditional micro-calorimetry techniques used to provide traceability for microwave power in this band whilst diversifying the potential applications and accessibility to such traceability. The thermopile of the measurement system was characterized using a known DC power with the microwave sensor and the thermopile coefficient obtained. Absolute microwave power on the microwave sensor was calculated using the thermopile coefficient and was used to remove the effect of a thermal isolation section and calorimeter unbalance effect. To transfer the power traceability from the calorimeter to microwave power measurement applications, the effective efficiency of a device under test, consisting of a power sensor/meter combination was defined using the calorimeter’s absolute microwave power and the S-parameters of the measurement system and of the device under test. The effective efficiency of the device under test was obtained between 0.9386 and 0.9815 for the whole frequency band.