Glide-Slope Antenna Arrays for Use under Adverse Siting Conditions

The problems of generation of an adequate glideslope signal on a practical airport site are examined, with particular attention to the path-shape degradation introduced by inadequate smooth surface in the primary reflecting area, and hills and similar mirror obstructions under the approach line. Quality factors are derived to establish comparison standards to evaluate the relative performance to be expected in application of various of the available arrays to any particular site. Two antenna arrays are described, which have been found in an extensive program of flight testing to provide substantial improvement in certain of these defective sites.