Under the hypothesis that the antenna’s lower plate is considered as an ideal infinite ground plane the input impedance
of the wearable antenna can be predicted by the equivalent circuit in Fig. 3. The above assumption is reasonable if the lower plate is a little larger than the upper antenna face hosting the microchip transponder. It is worth anticipating that both simula tive and experimental considerations, to be presented later on, will demonstrate that the antenna’s performance is very little sensitive to the placement on different parts of the body thanks to the previously discussed decoupling mechanisms.