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TECHNICAL FEATURE
The measurement of antenna axial ratios must be done properly if accurate resuits are to be obtained. When measuring on a terrestrial antenna test range, a straightforward approach is often used where-- by the circularly polarized antenna under test (AUT) (also referred to as receiving antenna) is rotated about its electrical boresight while being illuminated by a linearly polarized wave. Sometimes it may be more convenient to keep the AUT fixed and instead rotate the source antenna polarization. In either case, the difference between the maximum and minimum received signal levels is a direct indication of the AUT's axial ratio. This, of course, is not practical or even possible when using a circularly polarized signal from a satellite to measure the axial ratio of a ground-based antenna.
Two novel and accurate techniques for determining the axial ratio of a circularly polarized antenna were presented nearly 20 years ago by Stutzman and Overstreet.1 Their first method involves the use of two single or dual circularly polarized receiving antennas with measurements of...