Optically transparent antenna based on carrier-doped three-layer stacked graphene

We fabricated an optically transparent monopole antenna using graphene film and investigated the feasibility of the film as an electrode material for antennas. A low sheet resistance (80 Ω/sq) was attained by stacking the graphene films and carrier doping with an ionic liquid. The optical transmittance of the carrier-doped three-layer stacked graphene film was greater than 90%, enabling it to be embedded in highly transparent objects without altering their landscape. Using the monopole antenna structure with a metal ground plane, we measured the reflection and radiation characteristics of the graphene monopole antenna, excluding the contribution from the power feeding components. The radiation efficiency of the graphene monopole antenna, which was measured by the Wheeler cap method, was determined to be 52.5% at 9.8 GHz. Through the measurements of the graphene monopole antenna, we demonstrated that the carrier-doped three-layer stacked graphene film can be used as an electrode material for optically transparent antennas.