A HOMOGENEOUS DIELECTRIC SPHERE AS A MICROWAVE LENS
- 1 August 1956
- journal article
- Published by Canadian Science Publishing in Canadian Journal of Physics
- Vol. 34 (8), 790-803
- https://doi.org/10.1139/p56-089
Abstract
A homogeneous dielectric sphere illuminated by a small external source of electromagnetic radiation will be free, because of its special symmetry, from all off-axis aberrations such as coma and astigmatism. If the only monochromatic aberration, namely spherical aberration, is not too excessive or if it is partially corrected by a suitably designed source, a sphere could be used for purposes of rapid scanning of a microwave beam through an angle of 360° of arc without moving the lens. This possibility was investigated by computations based on geometrical optics and on the diffraction theory of optical aberrations. The results suggest that a sphere of fairly small refractive index and less than about 30 wavelengths in diameter will produce a good diffraction image of a point source. Methods are also discussed of designing appropriate sources for use with larger spheres.Keywords
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