Development of a class of antennas for space-based NAVSTAR GPS applications

The authors describe the performance of several unique antenna/ground plane configurations currently being developed for the TOPEX satellite and which may also be used for improved ground station operation. These antennas are designed with the objective of achieving nearly hemispherical coverage with sharp pattern cutoff above the horizon together with uniform phase response over the entire coverage area. The antenna under consideration consists of a Dorne-Margolin Model C146 antenna mounted on a variety of ground planes whose reflective surfaces have been modified to effect pattern control, particularly through the use of both tuned (Salisbury screen) and untuned absorbers and reactive ground planes consisting of concentric choke rings