Near-Field Curved-Beam Radiation Through Ray-Caustic Synthesis at Microwaves and Millimeter Waves

This study introduces a methodology for the synthesis of focused electromagnetic beams through the manipulation of ray caustics at microwave and millimeter-wave frequencies. In the realm of geometrical optics, caustics denote trajectories of high-intensity electromagnetic fields where optical rays converge. Such caustics may be efficiently employed to concentrate beams within the near field, directing them along predetermined spatial trajectories. The methodology discussed in this contribution allows introducing additional free parameters in the near-field synthesis procedure, thus enhancing the capability to produce versatile and curved focused beams. This approach can be considered an advancement with respect to traditional techniques for synthesizing nondiffractive beams, and holds significant potential for innovative communication systems and next-generation nearfield launcher designs.