Controlling sub-THz waves with graphene based devices

Carbon nanomaterials, such as carbon nanotubes and graphene, have attracted substantial interest in the electromagnetic domain due to their excellent electronical properties. The previous studies were mainly focusing on high frequencies, such as terahertz (THz), infrared and optical frequencies. However, the carbon nanomaterials also show potential applications in the microwave, millimeter wave, and sub-terahertz frequency domain. In this thesis, the research is mainly focused on the frequency domain below 1 THz, but not limited to it and on To investigate the graphene – the carbon material of utmost importance in this research work - based electromagnetic devices, the numerical methods of modeling graphene are implemented in the finite-difference frequency-domain (FDFD) and finite-difference time-domain (FDTD) schemes. With the numerical methods, the electromagnetic modulation properties of graphene in waveguide structures and free-space are investigated, and graphene based amplitude and phase modulators are designed in the millimeter and sub-terahertz wave frequency domain. Reconfigurable graphene based antennas and arrays are also studied. All this work is based on the single-layer graphene structure. Other carbon-based materials under study were screen-printed graphene and carbon nanotubes. The latter one was studied in the perspective of its polarization features. As such we could identify the anisotropy in seemingly random carbon nanotube network. Graphene screen-printed structures on flexible substrates are recently produced, which are the promising materials of printed flexible electronics. The flexible screen-printed graphene structures show properties of high absorption in the millimeter and sub-terahertz wave frequency domain. Based on these properties, metallic waveguide attenuators integrated with the screen-printed graphene and screen-printed graphene absorbers are proposed. The screen-printed graphene waveguide attenuators have low return loss and compact size. In conclusion carbon nanomaterial based electromagnetic devices are promising building blocks for the design and implementation of future electromagnetic systems.

Jaar van publicatie:2019

Trefwoorden:Millimeter Waves