A dielectric-lens aerial for wide-angle beam scanning

The paper deals with the design of dielectric lenses which produce, when illuminated by a suitable source of radiation, a beam capable of being scanned without distortion through a fairly large angle by moving the source. The treatment is restricted to aerial systems in which the radiation is guided between parallel plates to a long narrow rectangular aperture, the system being symmetrical about a central axis. It is shown that to avoid distortion when the beam is scanned, the rays from the focus and the final rays must meet on a circle about the focus (the sine condition). A dielectric lens which satisfies this condition and produces a beam of maximum gain in the direction of the axis can be designed. This necessitates the numerical integration of a differential equation which is discussed in the Appendix. It is also shown that for acertain range of values of the refractive index this lens can in practice be replaced by a plano-convex lens.