Effect of the Coaxial Dielectric Probe Diameter on Its Permittivity Sensing Depth at 2 GHz – Simulation Study

We previously reported the simulation results of the RG405-based open-ended coaxial probe model for biological tissue sensing depth analysis. The simulation model with this specific geometry proved valid for calculating the probe perceived permittivity at 2 GHz, triggering a follow-up study on the impact of the probe size on its permittivity sensing depth. In this study, the probe dimensions were upscaled up to five times, while keeping the same relative geometry to maintain the 50 Ω coaxial line impedance. The permittivity sensing depth was again analyzed on both the non-biological water-Teflon model, and biological layered tissue model. The results clearly showed the increased permittivity sensing depth of the larger probes with respect to the smaller ones, at 2 GHz. Nevertheless, the surface layer of the analyzed non-homogeneous samples was the dominant one for all probe sizes.