TABLE 2 ELEVATED ANTENNA RANGE RELATIONS FOR EQUAL TRANSMIT AND RECEIVE ANTENNA HEIGHTS tances greater than 6 D2/X are not practical, however, consideration for a mountain top to mountain top range with an elevation of 182.9 m (600 ft) and a measurement range of 11.33 km (7.04 miles) appears very attractive (see Table 2). A constraint on the absolute measurement accuracy of a far-field facility is calibration accuracy of a gain standard antenna. Commonly used calibration methods and approximate measurement accuracy are summarized in Table 3. Here, the calibration accuracy of even the best methods are almost an order of magnitude larger than desired for SPS antenna measurements. With the availability of a high stability microwave receiver, to be discussed later in this paper, it is anticipated that gain calibration to ±0.02 dB can be accomplished. Antenna Positioners The large weight handling requirement (2000 kg minimum),* and small angular accuracy requirements, indicate that the positioner is a potential problem area based *This weight estimate is based on ultra-thin aluminum waveguide with klystrons included. Fig. 1. Elevated antenna range concept.
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