The low-cost inhomogeneous multi-section flat lens antenna with minimum F over D design in Ku-band

This article uses the ray inserting method to design a low-cost inhomogeneous lens in the Ku-band. The focal length to the diametre ratio of the designed lens is 0.45, which is lower than most designed lenses in this area. Also, no approximation is considered to yield the refractive index profile. The refractive index changes from the centre to the sides have been made in two sections to limit the maximum calculated refractive index of the structure to the Plexiglass refractive index. The designed lens proposed a good match to the source and surroundings. The theoretical design is validated by the finite difference time domain scheme and full-wave simulation. The lens structure is realised and fabricated on a multilayer Plexiglass sheet. The results of simulations and experiments indicate good performances of the designed lens in the wide frequency bandwidth.