Banbury Radio Station
The story of Banbury Radio Station is very much linked to that of Devizes Wireless Station where we have been carrying out research over a number of years, including geophysical surveying. This link to Banbury and communications by Dave Sabin with Banbury Museum resulted in the writing of a short article for Cake and Cockhorse, Banbury Museum's Journal. The relationship between the sites is outlined below and the article is available as a PDF, although some photographs have been removed and replaced by URLs due to copyright. Banbury Radio Station PDF.
Devizes Wireless Station was constructed in 1913 and 1914 by Marconi as the British receiving station of the Imperial Wireless Chain, an incredible project designed to link up the British Empire. At the outbreak of WWI, the station was incomplete and by the end of 1914 the contract between Marconi and the government had been cancelled. In 1915 the Royal Engineers take over the site and make preparations for direction finding of enemy signals and intelligence gathering, this required a total change to the layout of the site which, most notably, resulted in the construction of the wireless station in the centre of the 2300m long aerial system rather than at the south eastern end as designed by Marconi. Direction finding was successfully pioneered at the site by H. J. Round, who also developed valve technology and the use of valves as amplifiers in receivers, and E.W.B. Gill, who was know for his work with wireless intelligence gathering, also spent some time at the site.
After the Armistice the site came under the control of the GPO. Not only had the station buildings, electronic and electrical systems, accommodation, etc. been established in a different location to the original design, but critically receiver sensitivity and selectivity had improved considerably through the wartime period as well as other factors such as radio propagation, aerial performance and electrical noise. These factors, combined with little political will or urgency to revive the Imperial Wireless Chain, influenced the conversion of the site by the GPO for long distance maritime communications for which the station became renowned. Political pressure from the Dominions eventually led to the revival of the Imperial Wireless Chain in 1921 and a suitable alternative receiving site was required.
The site at Bodicote Grounds Farm near Banbury was chosen probably because it met most of the original pre-WWI design elements, one of the main considerations being the requirement to be located at a right angle to the site of the British transmitter with respect to the great circle path to the Egyptian transmitter at Abu Zabal, the next link in the chain. The transmitter site remained at Langley near Leafield in Oxfordshire, as chosen for the pre-WWI scheme, and its aerial was aligned along the great circle path to Abu Sueir, the Egyptian receiving station. In the early days of wireless, stations used very long wire aerials and transmitted at very low frequencies. It was believed at this time that the aerial system radiated more power off the end where the station was located with significantly lower power at a right angle to the aerial's alignment, the need to minimise interference to the early receiving equipment was important and as such a minimum distance (12 miles) was required between the transmitter and receiver as well as their siting with respect to the great circle path to the next link in the chain.
Although the Banbury site may have been chosen with the above considerations in mind, there is no evidence that a long aerial, such as that required for Devizes, was ever constructed. Improvements in receiver design and better understanding of interference probably resulted in the use of much shorter truly directional aerials.