Porous low-loss silica–PMMA dielectric nanocomposite for high-frequency bullet lens applications

Several devices of the future generation wireless telecommunication technologies that use bands in THz frequencies for data transmission need low-loss and low-permittivity materials to enable ideal conditions for the propagation of electromagnetic waves. Herein, a lightweight dielectric bullet-shaped lens operating in the frequency range of 110–170 GHz is demonstrated to collimate electromagnetic waves, thus increasing the intensity of the electric field. The material of the lens is based on a composite of silica nanoshells and poly(methylmethacrylate) made by the impregnation of the nanoshells with the polymer followed by hot pressing in a mold. As the polymer acts only as an adhesive between the hollow nanospheres without filling the inner cavity of the shells and their interparticle spaces, the composite is highly porous (67%) and has low dielectric permittivity and loss tangent (1.5 and 4 × 10⁻³, respectively, below 200 GHz). The size of the collimated beam and the increase of the corresponding field strength are measured to vary from 2.2 to 1.2 mm and from 17.2 to 8.98 dB depending on the frequency of the waves (110–170 GHz).