Video transmitted at Terahertz frequencies

The test set consists of an emitter ...

The Physikalisch-Technische Bundesanstalt (German national metrology institute) has announced that Scientists at Terahertz Communications Lab in Braunschweig have transmitted an analog video signal across a distance of 22 metres at a frequency of 0.3 Terahertz (300 GHz). Terahertz Communications Lab has a number of contributors, including PTB and Braunschweig Technische Universität, who run three of the research group's four labs.

On the electromagnetic spectrum, Terahertz waves are found between infrared and microwave radiation. Until now, it has been considered difficult to generate the transmission power required for data transfer in this range. "Our experiment is the first step on a long journey. We soon plan to increase data rates and transfer one to two GBits/s", reports Christian Jastrow, a doctoral student at the PTB. According to the report, the scientists process the signal using Schottky diode mixers. Schottky diodes are particularly suitable for high frequency applications, due to their shorter switching times than those of conventional diodes.

... and a receiver unit, which outputs the video signal.

Moving to Terahertz waves to achieve data transmission rates of several Gigabits per second is inevitable since the comparatively low operating frequency of current systems such as WLANs (2.4 or 5.2 GHz) doesn't allow any further major data rate increases, said the report. However, the dramatically higher frequencies introduce new problems. Attenuation is much higher along the transmission path, and generating the necessary transmission power at 300 GHz is technologically demanding. Due to these two effects, data transmission only works over short distances and with line-of-sight connections, for example between HD video recorders and plasma TVs across a living room.

The trend towards higher transmission frequencies also exists in communication technology outside buildings: Swiss regulator BAKOM recently enabled a 4 GHz block at 60 GHz for digital microwave radio relay transmissions. According to the German Federal Network Agency a similar step can be expected in Germany before July 2008. No details about the terms of use have become available.

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(trk)