A 
design process first determines a desired aperture distribution, then converts the 
electric power conservation law, Snell's law on the rear face side of a 
dielectric lens, and the formula representing light-path-length constraint, into 
simultaneous equations, and computes the shapes of the surface and rear face of the 
dielectric lens depending on the azimuthal angle θ of a primary 
ray from the focal point of the 
dielectric lens to the rear face of the 
dielectric lens, and then reduces the light 
path length in the formula showing light-path-length constraint by an integral multiple of the 
wavelength when the coordinates on the surface of the 
dielectric lens reach a predetermined restriction thickness position. A 
dielectric lens is designed by sequentially changing the lazimuthal angle θ from its initial value, and also repeating the second and third steps. Thus, downsizing and quantification is realized by 
zoning while keeping antenna properties at the time of constituting a dielectric lens antenna in a good condition.