Comparative Study of RF Absorption Characteristics between Fatty and Fatless Tissue

The RF absorption in human body has received an acute attention for the health concerns. The goal of this study is to compare RF absorption characteristics by fatty- and fatless tissue to draw a comment where to keep or hold the RF device with respect to human body limbs. A square law detector on the receiving folded dipole antenna received 850 MHz signals from the sending dipole antenna in an antenna trainer experiment. Solid fatless-flesh and fatty-flesh goat meat were placed between the transmitting and receiving antennas 1.5 meters apart. The transmitting antenna was rotated from 0° to 360° with a 20° step size to measure RF absorption, although spline interpolation was utilized for analysis. When flesh was placed between antennae, detector current reduced compared to free space. Fatless flesh absorbed more RF power and was less transparent to RF signal due to its lower detector current. Estimated correlation, cross-covariance, and coherence between free-space current and fleshes were used to characterize RF absorption/penetration. Cross-correlation of free-space data with fatty-flesh is more than with fatless flesh with a value of 2.934 × 10 ⁵ and 2.499 × 10 ⁵ respectively at zero-degree lag. It indicated that the fatty-flesh is more transparent to RF signal than its fatless twin. In coherence analysis with respect to free-space data, magnitude-squared coherence using Welch method revealed that fatless-tissue got phase lagging of 7.067° in contrast to its fatty counterpart measured at the minimum coherence level. It indicated that this tissue is less transparent to RF signal and absorbs more RF power than fatless-tissue.