New broadband thermal noise primary standard in coaxial technology

Abstract

-A broadband primary standard for thermal noise measurements is presented and its thermal and electromagnetic behavior is analyzed by means of analytical and numerical simulation techniques. It consists of a broadband termination connected to a 3.5mm coaxial airline partially immersed in liquid Nitrogen. The main innovative part of the device is the thermal bead between inner and outer conductors, designed for obtaining a proper thermal contact and to keep low both its contribution to the total thermal noise and its reflectivity. A sensitivity analysis is realized in order to fix the manufacturing tolerances for a proper performance in the range 10MHz-26.5GHz.

Analysis of noise temperature sensitivity for the design of a broadband thermal noise primary standard

“…In [14] tapered designs, continuous and stepped, were presented. In this solution, the transitions are partially filled with boron nitride in order to keep the 50 £2 continuity.…”

“…Adjacent transitions to the bead are needed in order to reduce the bead reflectivity. In [14] tapered designs, continuous and stepped, were presented. In this solution, the transitions are partially filled with boron nitride in order to keep the 50 continuity.…”

“…Figure 7 shows the design for the 6 mm bead, and figure 8 the magnitude of the scattering parameters s 11 and s 21 for both beads. As compared with the tapered design [14] Table 1. Dielectric and thermal properties of bead materials.…”

Análisis y diseño de un patrón de ruido térmico de 10 MHz a 26,5 GHz en tecnología coaxial

“…Como en el caso de los orificios, el método utilizado es el FEFD. Con el fin de reducir la reflectividad de la pieza dieléctrica se han diseñado varias piezas con transiciones diferentes; en [FOR11] se presentan varias soluciones con variaciones continuas o abruptas de estas transiciones que están parcialmente ocupadas por BN para mantener constante su impedancia característica.…”