Low-loss HF carbon nanotubes

A collaboration between researchers at the University of Surrey’s Advanced Technology Institute and the Faculty of Mechatronics of Warsaw University of Technology in Poland has shown that low electrical loss at frequencies up to 220 GHz are possible in screen-printed carbon nanotube-polymer composites.

Producing such low electrical loss materials potentially opens up new types of high-frequency large-area electronic devices.

A carbon nanotube is a rolled up sheet of graphene that has a diameter of a few nanometres. This size is equivalent to thousandths of the diameter of a human hair but, despite their small size, CNTs have outstanding properties such as high strength and an ability to carry a very high current.

The study shows that CNT composites have electrical losses of less than 0.3 dB/mm over a wide frequency range. Embedding CNTs in a polymer, in this case PMMA, allows accurate control of the nanotube content and control over the conductive phase of the composite which was screen-printed into coplanar waveguides to produce structures tens of millimetres long.

Using a screen printing allows easy scalability for production and relaxes many of the constraints found in high-end manufacturing techniques. Possible applications include new types of microwave mixers, phase shifters and antennas.