Ka-Band Quasi-Nondiffraction Beam Generation Through a Broadband Bessel Lens Antenna

A broadband Bessel lens antenna with stable quasi-nondiffraction range and considerable broadband characteristics is designed and fabricated. The theoretical basis and operating principles for the broadband near-field quasi-nondiffraction antenna are introduced. Then, design procedure for the structure of the Bessel lens is discussed in detail. Considering the influence of oblique incidence waves, phase shifts of the lens elements with different incident angles are simulated, and interpolation analysis method is applied for the lens modeling to minimize phase error. The proposed lens antenna can be used as a Bessel beam launcher operating at 26-32 GHz. The lens structure is fabricated using 3D-printing and fed by a dual-mode conical horn. Measured results agree well with the simulation.