Lens antennas are widely used in RF technology for various purposes along with parabolic mirror antennas due to their ability to form a narrow beam pattern. With the same aperture area, the lens antennas provide almost the same level of gain as the mirror ones. However, in some cases, the use of lens antennas has undeniable advantages.
So-called Luneberg lenses possess unique properties. The idea of spherical lenses with inhomogeneous dielectric filling, focusing incident parallel rays at a point on the surface of the sphere, belongs to the German mathematician Rudolf Luneberg. Unlike standard thin lenses having one optical axis, Luneberg lenses have spherical symmetry, which will determine their ability to work simultaneously in many directions in space. In particular, Luneberg microwave lenses also have this feature. To implement a Luneberg lens on a microwave, we propose the use of an artificial material consisting of thin radial dielectric rods.
We also made a ultrawide-band planar antennas with multi-frequency notched filters, made in the form of a round metal plate fed by a coplanar waveguide.