Wavelength Lenses

The operation of a polyrod antenna can be considered as that of a lens having cross-section dimensions of the order of a wavelength. The sides of this lens are shown to be responsible for the concentration of energy, and this gathering action continues with increasing length up to a point where the energy inside the lens traveling slower than light falls out of phase with the external energy. The velocity of energy inside the lens is a function primarily of the lens dimension in the E plane of the wave. There exists an optimum length for each lens at which the energy is maximum. If these maxima are plotted against the lens aperture, a well-defined minimum is obtained at an aperture of one square wavelength. Below this point energy increases with decreasing cross section in the wavelength lens region, and above this point energy increases with increasing cross section in the optical lens region.