rectenna parameters may be summarized as follows: Total Active Panel Area: 78.5 km^ Configuration; Panels (multiple antenna elements feeding a single diode. Panels should be openfaced to reduce wind loading, with a maximum of 1% leakage energy. Receive Elements: Half-wave rectifying diodes. To provide an estimate of the power levels around the rectenna, studies indicate that the dipoles have 98% collection efficiency under normal loading conditions (reference 9). The 2% reflected microwave power is directed upward and towards the southern horizon. This reflected energy at 2.45 GHz is only partially coherent since the regions of coherence for the incident beam are limited due to phase irregularities in the heated ionosphere and atmosphere. Harmonics of 2.45 GHz will be generated within the half-wave rectifying diodes and will be reradiated back through the low-pass filters and dipoles. Initial measurements of the harmonic levels relative to the fundamental indicate the second, third, and fourth harmonics are down by -25 dB, -40 dB, and ^70 dB, respectively, for the normal dipole/diode rectifier configuration (reference 9). There will also be leakage power through the rectenna. For a ground plane transparency of 80%, approximately 1% of the incident power appears as leakage through the wire mesh. Since the rectenna's receiving surface appears serrated with individual panels perpendicular to the incident radiation, there will be diffraction losses at the top edge of each section. An analysis of the knife edge diffraction pattern has been made to determine the variation in power density incident upon the adjacent rectenna section (reference 9). The power density will vary in the shadow region (area behind the rectenna section) as shown in figure 24. It may be necessary to extend the size of the rectenna section to intercept part of the shadow region. There will also be energy lost as heat in the rectenna due to
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