The design of an automated, high-accuracy antenna test facility

The application of far-field range and instrumentation techniques to the design of a facility for testing the in-orbit far-zone operating characteristics of communications satellite antennas is presented. Electromagnetic and geographic design factors are considered, and the range parameters given in detail; the design of the 7850-foot range is shown to have limited overall extraneous signal level to a maximum value of -37 dB relative to the direct-path signal level, and to have minimized the effect of changes in temperature, index of refraction or cable length by making test and reference arms of equal length and using the same cable. The design of the test enclosure, which kept extraneous signal levels 45 dB below signal level, is described. The facility can be operated in the 4-, 6-, 11-, and 14-GHz common carrier bands and is shown to meet the 10 D-squared/lambda criteria to ensure adequate beam formation to model the infinite range length pattern over the main beam and peak areas of the sidelobes. The computerized range instrumentation, employing a test-on-transmit configuration, is found to produce an overall test-facility uncertainty of + or - 0.6 dB when measuring -30-dB sidelobe levels.