Beam elevation positioning in geodesic lenses

A class of circularly symmetric geodesic lens antennas are considered in which each lens can be designed for any single beam elevation position. This paper investigates a method for controlling beam elevation in a single lens. The beam is positioned in elevation by radial feed movement and the theory for off-focus behavior of geodesic lenses is given. Since the beam can also be scanned around the symmetry axis, volumetric coverage is possible. A particular lens design (\beta=40\deg, r_{1}=0.82) is given by which the beam can be positioned over a wide range of beam elevations. A TEM lens model and a dual polarization lens model using both TEM andTE_{01}modes were tested atX-band. The beam was positioned from an angle of25\degwith respect to the plane of the lens rim to broadside for the TEM mode by simply moving the feed from near the rim to the center of the lens.