cal and mechanical errors is approximately 6.7% (96% rectenna collection efficiency for an error-free single beam system versus 89.3% with errors). The effects of errors upon the rectenna collection efficiency for single and multiple beams are shown in Fig. 8. These results are summarized in Table 2. The efficiency degradation due to electrical and mechanical errors is 6.1% for multiple beams. This degradation in beam performance due to errors is approximately the same for single beam and multiple beam systems. The data also indicates only a 1.2% degradation in collection efficiency due to dividing the beam into multiple components which is less than the 2% tolerance recommended previously. Effects of Satellite Motion A question arose as to the effects of satellite motion upon the amplitude taper across the antenna. Each satellite has nonstationary, elliptical motion in geosynchronous orbit. The maximum distance variation between the satellite and the rectennas in a 24-h period is expected to be approximately 1 km. Since the vectors from the rectennas to an individual subarray receiver will vary many wavelengths in phase over a 24-h period, there could be a problem in continuously adjusting the amplitude or power output from each subarray. However, the simulations indicate these pathlength variations result in less than 1% difference in amplitude taper. Satellite motion should not therefore have any adverse effects upon the antenna's operational capability to accommodate phase and amplitude fluctuations. CONCLUSIONS AND RECOMMENDATIONS The relative sizes and performance characteristics for three multiple beam systems are compared to the 10 dB Gaussian reference system in Fig. 9. The multiple beam systems are sized according to various ionospheric (/„) and thermal (T„) limits. Each of these systems has superior performance to the single beam reference configuration. The advantages of multiple beam systems may be summarized as follow: • Allows operational flexibility;
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