Satellite-antenna measurement techniques

Initially, the review takes a brief look at the various types of antenna systems that are used on satellites and shows that in terms of the measurement of their radiation characteristics, they can be categorised into two groups, i.e. low-gain (omnidirectional and quasi-omnidirectional) antennas, and medium- and high-gain antennas. With the first group, the main measurement difficulty lies with the suppression of multipath reflections, and the various range configurations that can be used to avoid or overcome this problem are described. Two of these are, for example, the ground reflection mode range and the use of baffles within an anechoic chamber. Following this, direct measurement ranges applicable to medium- and high-gain antennas are reviewed. These far-field approximation test range configurations include the elevated mode range, either in an outdoor environment or within an anechoic chamber, and the semi-open anechoic chamber. Subsequently, the review considers the various near-field and intermediate distance methods. Finally, some special techniques that have been devised to examine some particular satellite-antenna problems, such as the determination of the r.f. transparency of launch vehicle fairings and the effect of conductive thermal-control paint on satellite-reflector antennas, are presented. The review is principally from a European viewpoint.