Automation of Direct Comparison Technique and Study of long term Performance on the Calibration factor of the Thermistor Mounts in N- type Coaxial line upto 18 GHz

Abstract

National Physical Laboratory (NPL) of India is the premier research & development center and the National Metrology Institute, which provides traceability in measurements by calibration throughout the country. Radio Frequency (RF) power is one of the most important quantities in RF metrology. The measurement of calibration factor for thermistor mounts by direct comparison technique in the frequency range of 50 MHz to 18 GHz and its automation is presented in this paper. The automation of this technique makes calibration faster and more accurate through GPIB cables using IEEE-488 interface card. The software for this technique has been developed using the VEE Pro application, which is a graphical programming environment optimized for use with the electronic instruments. It also minimizes the human involvement and therefore reduces the chances of errors. The stability performance study carried out on three different thermistor mounts by the direct comparison technique is reviewed in this paper. The results show that the maximum deviation in the calibration factor of the thermistor mounts from the reference value over the years is within ± 1.5 % from 50 MHz to 18 GHz.

An Adiabatic Coaxial Line for Microcalorimeter Power Measurements in Wireless Communication for Smart Grid

“…Compared to the results published in the literature (e.g. [7,11]), we obtained a slightly better transmission coefficient in the mid-range of frequencies spanning from approximately 1.5 GHz to 4 GHz, where line is very well matched (S11 < −20 dB). In particular, compared to results in [7], in the frequency range 4-6 GHz our results are similar or even slightly better.…”

“…[7,11]), we obtained a slightly better transmission coefficient in the mid-range of frequencies spanning from approximately 1.5 GHz to 4 GHz, where line is very well matched (S 11 < −20 dB). In particular, compared to results in [7], in the frequency range 4-6 GHz our results are similar or even slightly better. On the other hand, comparing our results with [11], we noted across the vast portion of range of interest that we have measured transmission parameter magnitude (S 21 ) larger than −0.5 dB (Figure 18), while in [11] the S 21 parameter magnitude is lower than −1 dB for all observed frequencies.…”

“…For calibration factor determination of the commercial thermistor mounts, as well as for the primary power standards, devices named microcalorimeters are nowadays most commonly used due to their high stability in terms of parameters that determine detector efficiency. The thermistor mounts present common transfer power standards in the power range of mW, where most personal communication systems operate [2][3][4][5][6][7].…”