A Ka-Band Metallic Mikaelian Lens Antenna Based on Bed of Nails with Continuous Gradient

This paper presents a Ka-band fully metallic Mikaelian lens antenna. The antenna is comprised of a parallel plate waveguide with a bed of metallic nails on the base plate, which is fed by five WR-28 waveguides. By adjusting the height of the nails while maintaining the fixed spacing of the parallel plate waveguide, the desired refractive index distribution is achieved. Full-wave simulation results demonstrate reflection coefficients below -12.4 dB, coupling coefficients below -18.5 dB and a beam scanning range of ±30° within the 26 GHz to 32 GHz band. Additionally, sidelobe levels are lower than -7.5 dB, and the maximum gain are higher than 14.5dBi.