Characterisation of tunable graphene antenna

Graphene is a unique material that can display tuning characteristics. This characteristic originates from its surface complex conductivity, which is controlled by a chemical potential. Most characteristics of tunable graphene antenna have been studied on Terahertz frequency range, thus making it difficult to be realised practically. Besides that, the standard antenna that uses switching components may have trouble during installation, and consume size as can be seen in the reconfigurable antenna. With the integration of this material, a tunable antenna based on graphene operating at microwave frequency range is proposed. The antenna was designed and fabricated at 15 GHz with a gate electrode placed behind it. They are connected to external DC bias during the measurement. The biasing is applied from 0 V to 30 V. The result shows that resonance frequency tuned about 20 MHz and reflection coefficient magnitude improved 1.24 dB. Following this, an analytical calculation on chemical potential was also derived for enhancing the graphene tunability. The count shows that at least 2.85 kV of the gate voltage is needed to vary the chemical potential and less than 0.26 µm of dielectric spacer thickness is suitable for tuning with a given condition, respectively.