Development of millimetre-wave quasi-optical devices based on the mesh technology

Photolithographic techniques have been used for decades to manufacture mesh filters at millimetre and sub-millimetre wavelengths. These frequency selective devices, based on metal grids with sub-wavelength periodic structures, have found many applications, especially in astronomical instrumentation. Given the modeling and manufacturing accuracies achieved recently, the same mesh technology has been adopted to develop more complex devices based on anisotropic and inhomogeneous surfaces. It is also now possible to design more exotic devices such as those required to manipulate the Orbital Angular Momentum (OAM) of the radiation.