0191-9067/81/010073-14S02.00/0 Copyright 1981 SUNSAT Energy Council SOLAR POWER SATELLITE (SPS) ANTENNA MEASUREMENT CONSIDERATIONS D. J. KOZAKOFF, J. M. SCHUCHARDT, and J. W. DEES Georgia Institute of Technology Engineering Experiment Station Atlanta, Georgia 30332, USA Abstract — The relatively large subarrays (tens of meters) to be used in the solar power satellite (SPS) (1) and the desire to accurately quantify antenna performance dictate the requirement for specialized measurement techniques. An investigation conducted at the Georgia Institute of Technology (2) has quantified the error contributors associated with both far-field and near-field antenna measurement concepts. As a result, instrumentation configurations were identified with desired measurement accuracy potential. In every case, advances in the state-of-the-art of associated electronics were found to be required. Relative cost trade-offs between a candidate far-field elevated antenna range and a near-field facility were also performed. INTRODUCTION A recent investigation at the Georgia Institute of Technology has addressed the following SPS antenna technology issues: 1. For 10 m2 antenna subarray panels, quantify considerations for measuring power in the transmit beam* to ±0.04 dB (±1.0%) accuracy. 2. Evaluate measurement performance potential of far- and near-field antenna measurement techniques. 3. Study performance impact on the required microwave instrumentation and measurement sites. 4. Perform relative cost trade-offs between candidate far-field and near-field facility concepts. An antenna measurement error adopted earlier in the study budget is shown in Table 1. Measurement errors have been quantified into four sources: antenna range, structural/environmental, transmitter, and receiver. The objective of this study was to control error sources to yield an overall gain uncertainty of ±0.04 dB. Because of the large size of a subarray (81.67 wavelengths at 2.45 GHz), the antenna range error was allotted the largest allowance in the error budget. *Maximum total klystron transmit power is 32 kW per subarray.
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