Dorking & District Radio Society

Recent Meetings and Events

Beacon Hunting

25 May 2021

Club members and visitors gathered at Headley Heath for a fun evening outdoors, practising radio direction finding. Using 3-element "tape measure" antennas and simple receivers provided by Denis Noe, we set about locating small transmitters hidden among the trees.

Spectrum Analyser Project

27 April 2021

David Wilde demonstrated his DIY spectrum analyser, which he designed and built around a standard digital processing chip. He explained the process to get a multi-layer PCB manufactured, the use of a surface acoustic wave filter, digital filtering to sample the incoming signal by frequency, and a browser interface for user interaction. He also described some commercially available spectrum analysers.

Orbital to Linear Angular Momentum

23 March 2021

Tim Brown and Ben Allen jointly explained how multiple antennas with suitable phasing delays could be used to create radiation with "orbital momentum", rotating around as they travel along. Using different rates and directions of rotation, multiple channels can be created on the same frequency, increasing the total bandwidth. An analoguous approach using antennas spaced linearly, alongside a railway track for example, could be used to enable broadband communication with moving trains, without the need for intrusive masts in rural areas. This was demonstrated using models and amateur radio equipment.

Propagation Prediction using the Chilton Ionosonde

23 February 2021

Philip Miller Tate gave some background information to the ionosonde at Chilton, OxfordShire, and showed us various examples of the ionograms it produces. He explained the structure and nature of the ionosphere, and how to interpret the ionograms to deduce likely propagation conditions.

Mr Marconi and his Marvellous Invention

26 January 2021

Dr Liz Bruton, a curator at the Science Museum, told the story of how early radio technology progressed from a short range demonstration on Salisbury Plain; to the first live reporting from a ship of a yacht race in Ireland; and to enabling the Titanic to call for help and thus save hundreds of lives. That fateful night was documented minute by minute in the telegraphic communications with other ships, which Liz poignantly described.