Improved gain-transfer method for long antennas

When the incident field in the quiet zone of an antenna test range is not an uniform plane wave over the apertures of both the antenna under test (AUT) and the standard-gain horn (SGH), the gain-transfer method will produce erroneous measurement results. An improved gain-transfer method is described here to reduce such measurement errors when long antennas are measured in a limited-size quiet zone. Under such conditions, the aperture of the AUT is usually much longer than that of the SGH and therefore these antennas will typically be exposed to different variations in the incident field. It is shown here how the measurement errors can be reduced significantly by using multiple measurement positions for the SGH instead of the traditional single measurement position.