Effect of Soil and Antenna Polarization on the Wireless Performance of Smart Insoles

This work highlights the influence of the soil dielectrics and antenna polarization in the case of mobile nodes of smart insoles. Polarization mismatch is clearly happening during the gait and implies high variation in the received power. We characterized this loss for several polarization and dielectric soil properties. The results shows that the relative permittivity of soil in the range $1-10$ implies bigger variation in the received power compared to the range $10^{-9}-1$ ($3 \mathrm{~dB}$ vs $\ll 1 \mathrm{~dB}$). The range $0.1-1 \mathrm{~S} / \mathrm{m}$ for conductivity is also impactful in the received power. Concerning polarization, results show the impact of foot tilt and deviation on the $S_{21}$ magnitude and variation of $-20 \mathrm{~dB}$ were observed.