Figure 3
(a) The real part (conductance) of the input admittance of an equivalent Butterworth Van Dyke (BVD) circuit, which is a Lorentzian, is plotted for six measured angles of Device A at a 28-inch distance from the fixed bi-conical antenna. The recorded S21 parameter data were used to extract the lumped circuit elements values, which were then used to calculate the real and imaginary parts of the input admittance of the BVD circuit. At each distance, a total of twelve angular measurements were taken, although only six are presented for easier viewing. (b) The distance dependence of wireless actuation for Device A is presented. As before, only six (guide-to-eye) plots are presented for easy viewing. A gradual decline is expected with increasing distance; however, owing to near-field effects, multipath interference and reflections less than the ideal response are observed. (c) Angular dependence of Device A is presented for 6, 8, 10, and 12 inches. Being linearly polarized, the top-patch electrodes are expected to receive varying amounts of E-field as the in-plane angle theta (θ) of the resonator is changed from 0 to 330 degrees. However, it is noteworthy that with increasing distance, this dependence diminishes, possibly due to increased reflections of the waves. As the distance is increased beyond 12 inches, this dependence diminishes further, and only flat plots (not shown) for angular dependence are observed. (d) Distance dependence of efficiency for Device A is presented with maximum efficiency of ~3% at 16 inches. The efficiency is the ratio of the output power from the device to the input power irradiating the device at each distance.
