Microcalorimeter for 7 mm coaxial transmission line

Abstract

Certain commercial components used in the microcalorimeter are identified in this document in order to adequately specify the design. Such use and identification does not imply recommendation or endorsement by NIST, nor does it imply that the identified items are necessarily the best available for the purpose. The International System of Units (SI) is used except in the dimensioned part drawings found in appendix B. The shop which made these parts was not equipped to use metric dimensions, Financial resources are not currently available to convert the drawings to SI units. IV

Development of a Type-N Coaxial Microcalorimeter for RF and Microwave Power Standards at KRISS

“…To achieve a seamless replacement of the microcalorimeter, we decided to develop a new type-N coaxial microcalorimeter in 2010. The structure of the new microcalorimeter is similar to our previous microcalorimeters [3], [4], and we referred to well-made calorimeters [7]- [10] to optimize the performance of the new one. It has a dry-type triple metal shield thermostat, twin adiabatic lines, and a thin-film thermopile module.…”

Proposal of a Super-Symmetric Microcalorimeter for Single Step Realization of RF Primary Power Standard

“…In the first step, the power sensor under test is fed alternately with the RF power and the reference power, respectively, and a raw effective efficiency of the power sensor is calculated [4].The second step is necessary to make corrections to the contribution of the microcalorimeter feeding lines. Unfortunately, several problems arise in the calibration step, including microcalorimeter dismount/mount operations, long-term thermal equilibrium, inherent uncontrollable changes in the thermal paths, differences between the power levels adjusted for each step, and very low measured values [1][2][3][4][5].…”

“…The manner in which this system works has been widely discussed in the relevant literature by other researchers [1][2][3] and by us [4][5][6]. However, independent of the technical solution adopted in each laboratory, the effective efficiency of the power sensor used as the calorimetric load can be expressed as the rational function of sensor mount temperatures.…”

Error in calorimetric effective efficiency measurements due to DC losses

“…NIST's Type N coaxial microwave power standards consist of a microcalorimeter [1] and a set of CN mount power sensors [2]. The CN sensing element is a type of temperature sensitive resistor called a thermistor that absorbs both direct current (DC) and radio frequency (RF) or microwave power.…”

“…The effective efficiency is determined from the thermopile and bias signals using the following [1]: …”