Validation of a Broadband Tissue-Equivalent Liquid for SAR Measurement and Monitoring of Its Dielectric Properties for Use in a Sealed Phantom

Abstract

We report on the development of a method for measuring the permittivity and conductivity of fluids inside a sealed tank (or a pipe) by using an embedded coaxial probe. Permittivity and conductivity in the frequency range 600 MHz to 6 GHz are determined from measurements of a complex reflection coefficient by using a vector network analyser (VNA) that is connected to the embedded probe via a coaxial cable. Substitution methods for calibration of an inaccessible probe are studied in this paper. These require the VNA with attached cable to be calibrated prior to connecting the cable to the embedded coaxial probe. Measurement of permittivity and conductivity of fluids inside sealed tanks and pipes is needed for monitoring industrial processes, such as fermentation. The authors’ requirement, however, was to allow monitoring of a tissue-equivalent liquid that is contained inside a sealed tank. This tank is a component of a commercial system for rapid, multiple-band measurement of the specific absorption rate (SAR) of mobile phone handsets. Monitoring of permittivity and conductivity is needed to ensure compliance with international standards for SAR measurement. The paper also presents data for a new broadband (600 MHz to 6 GHz) tissue-equivalent liquid that is based on an oil-in-water emulsion. It is demonstrated that over an extended period of time, the liquid is stable, and an embedded coaxial probe enables its properties to be monitored with the required accuracy.

Design and analysis of circular microstrip patch probe array for precise specific absorption rate measurement at quad-band

“…The obtained E-filed values are measured by using the proposed design, and after comparison of Tables 3 and 4, the obtained SAR values are within the standard limits. As per IEC-62209-1,2,3/IEEE 1528 [25–27], the circular probe array each source of uncertainty budget evaluation has been performed as shown in Table 5. Soh et al .…”

“…The obtained E-filed values are measured by using the proposed design, and after comparison of Tables 3 and 4, the obtained SAR values are within the standard limits. As per IEC-62209-1,2,3/IEEE 1528 [25][26][27], the circular probe array each source of uncertainty budget evaluation has been performed as shown in Table 5. Soh et al have reported a SAR value of 0.54 W/kg in reference [28], but the proposed work obtained a SAR value of 0.24 W/kg; the difference may vary due to the repeatability of the test.…”