Numerical methods make lens antennas practical
Abstract
A numerical computer scheme for efficiently shaping the contours of a coma-free dielectric lens for uses above the Ku-band is presented. Design techniques retained from shaping reflector antennas include path-length constraint, application of Shell's law at the boundary, and aperture power distribution to control the beam shape and the level of side lobes. Imposing the Abbe sine condition instead of a power conservation law eliminates cubic phase errors for off-axis scans. Steps to setting up the geometry of the lens are detailed, including direct integration of the differential equations defining the profile of the lens sides. Iteration is necessary to optimize a final design. The fabrication of a prototype lens with a 2.54 dielectric constant, a 22 cm diameter, a center thickness of 5 cm, and an effective focal length of 29 cm using a numerical step size of 0.1 deg is described. The lens performance is noted to be close to the model predictions
- Publication:
-
Microwaves
- Pub Date:
- September 1982
- Bibcode:
- 1982MicWa..21...81L
- Keywords:
-
- Antenna Design;
- Antenna Radiation Patterns;
- Computer Aided Design;
- Lens Antennas;
- Dielectrics;
- Far Fields;
- Numerical Integration;
- Prototypes;
- Sidelobe Reduction;
- Electronics and Electrical Engineering