Figures 2-12 and 2-13 in conjunction with other readouts from the computer simulation program, permit a number of statements to be made about the behavior of the rectenna element. 1. There are no current or voltage spikes whose presence, if severe, is usually associated with a life failure mechanism. 2. In Figure 2-13 it will be seen by observing the diode junction voltage Vpj as it swings into the positive voltage region, that the conduction period is about 105 . 3. There is a large amount of diode current flow during the non-conduction period which is caused by the charging and discharging of the diode capacitance. This represents a loss as the charging current must flow through the series resistance of the diode. It will be recalled that the series resistance in the forward direction remains constant during the forward conduction cycle but decreases considerably as the voltage swings away from the zero-bias value. The total loss in the series resistance integrated over the entire cycle as printed out is 121. 7 milliwatts or 3. 73% of the input power. Of this, 82 milliwatts or 2. 52% is represented by losses in the series resistance of the diode in the forward conduction period; while 40 milliwatts or 1. 23% represents a loss through this resistance in the reverse direction. The loss in the Schottky junction itself is 170 milliwatts or 5. 22% of the input power. Finally, the skin losses in the rectenna element amount to 68 milliwatts or 2. 08%. The total losses as given by the computer simulation program are therefore 11.03% of the power input. This compares well with 12. 8% obtained experimentally as noted in Table 2-1. It compares more closely if a Schottky junction voltage drop of 0. 9 volts observed experimentally is used in place of the 0. 65 volts assumed theoretically. Under these circurr stances the Schottky junction loss becomes 7. 22% and the total losses become 13.03% - very close to the 12.8% observed experimenr tally. 4. It will be noted that there is a small amount of ripple on the output filter capacitance. The maximum voltage is 15.8 volts and the minimum is 15. 1. When this ripple is broken down into the harmonics, the first harmonic is found to have an rms value of 0. 246 volts, representing a power in the load resistance of 0.75 milliwatts. The second harmonic is down by almost a factor of 100 from this value.
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