Extraction of frequency-dependent reflection, transmission, and scattering parameters for short metal reflectors from FEM-BEM simulations

Reflectors comprised of only a single or a few electrodes provide controllable, weak reflectivity essential for surface acoustic wave (SAW) radio-frequency identification (RFID) tags. The reflection, transmission, and scattering parameters of such reflectors must be known as a function of frequency in order to be able to control the amplitudes of tag responses and to use phase-based encoding reliably. In this work, we present a method of extracting the main reflection, transmission, and scattering parameters for short metal reflectors as a function of frequency. We use test device S parameters obtained through finite- and boundary-element method (FEM-BEM)-based simulations and, as an example, determine the reflection and transmission coefficients (their absolute values and phase angles) and the energy scattered into bulk for a few different single-electrode reflectors. We compare these parameter values to earlier results. Although only used for simulated data in this work, the same method can be applied to measured data as well. Assuming the S parameters available, this method is very fast and does not require any heavy calculation or special software.