Lightweight porous silica foams with extreme-low dielectric permittivity and loss for future 6G wireless communication technologies
low-permittivity materials, low-loss dielectrics, templated sol-gel synthesis, silica foams, 6G telecommunication
In the next generation wireless communication systems operating at near terahertz frequencies, dielectric substrates with the lowest possible permittivity and loss factor are becoming essential. In this work, highly porous (98.9% ± 0.1%) and lightweight silica foams (0.025 ± 0.005 g/cm3), that have extremely low relative permittivity (εr = 1.018 ± 0.003 at 300 GHz) and corresponding loss factor (tan δ < 3 × 10-4 at 300 GHz) are synthetized by a template-assisted sol-gel method. After dip-coating the slabs of foams with a thin film of cellulose nanofibers, sufficiently smooth surfaces are obtained, on which it is convenient to deposit electrically conductive planar thin films of metals important for applications in electronics and telecommunication devices. Here, micropatterns of Ag thin films are sputtered on the substrates through a shadow mask to demonstrate double split-ring resonator metamaterial structures as radio frequency filters operating in the sub-THz band.
Tsinghua University Press
Petra S. Pálvölgyi, Daniel Sebők, Imre Szenti, Eva Bozo, Henri Ervasti, Olli Pitkänen, Jari Hannu, Heli Jantunen, Marko E. Leinonen, Sami Myllymäki, Akos Kukovecz, Krisztian Kordas. Lightweight porous silica foams with extreme-low dielectric permittivity and loss for future 6G wireless communication technologies. Nano Research 2021, 14(5): 1450-1456.