Generation of bessel beam in millimeter wave band by phase-shifting lens

A dielectric phase-shifting lens, which can convert an incident Gaussian beam in millimeter wave band to be a Bessel beam, is designed. The phase-shifting lens is a dielectric disc filled with different unit cell, which drilled with air holes with different diameters in the dielectric substrate. The transverse intensity pattern of the generated Bessel beam is plotted, which shows that the phase-shifting lens has a good conversion performance. The generated zero-order Bessel beam has a very narrow beam in the center and can propagate a certain distance suffering only a little diffraction.