NEAR-FIELD MEASUREMENTS General Considerations Near-field techniques utilize a calibrated probe antenna to measure the amplitude and phase of the field close to the antenna aperture. A single linear-polarized probe oriented in the vertical and horizontal directions are used, together with a probe compensation technique to obtain the complete radiation characteristics of the antenna under test. This technique requires instrumentation capable of reading the measured data in digital form required for computer processing. The planar near- field measurement technique is particularly attractive for SPS since the SPS subarray does not have to be moved during the measurement, i.e., only the probe antenna is moved. Martin Marietta (4) has implemented an indoor planar near-field measurement facility capable of measurement of antennas up to about 15 m in diameter. The benefits of this facility include all weather operation, a thermally controlled enTABLE4 ERROR SUB-BUDGET FOR RECEIVER ELECTRONICS
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