Effect of Radio Frequency Signals on Resistive Measurements of Temperature

Abstract

In many situations, the measurement of temperature is done with resistive sensors. This is the case with standard platinum resistance thermometers (SPRTs), industrial level PRTs, resistance temperature detectors (RTDs) and thermistors. There are many possible sources of uncertainty in these measurements. One potential source of error that may be difficult to quantify is the error due to radio frequency (RF) signals. This paper presents data from experimentation done with radio signals close to a temperature measurement location. While the data presented in this paper were not taken in a controlled RF measurement laboratory, they are done in a practical situation. The factors such a type of antenna used, walls between the antenna and measuring sensor, distance between the measuring sensor, and the RF source and length of the temperature sensor leads are disclosed. Different factors are considered such as frequency of the RF signal, power of the RF signal, resistance of the temperature probe and length of the temperature probe leads. Amateur radio equipment is used for the RF signal generation in the high frequency (HF), very high frequency (VHF) and ultra high frequency (UHF) bands. The author uses his knowledge of both amateur radio equipment and temperature metrology to present and analyze the data.