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TOLWORTH TOWER
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 It's good to have Radio Jackie back! The transmitter may be only 100 Watts, but it can be heard from Caterham to High Wycombe, thanks to the antenna being sited 75 meters above ground level, on top of the Tolworth Tower - the Marks And Spencer building. The main service area is South West London, including Kingston Upon Thames, Walton upon Thames, Sutton, Cheam, Weybridge, Cobham, Esher and Epsom. |
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The Sira type mixed polarisation antenna is fitted with a reflector, facing South-West - thereby minimising signals radiating towards central London. The main signal radiates towards Epsom, Leatherhead, Cobham and Weybridge, though Radio Jackie's service area is much wider, including Kingston upon Thames, Sutton, Cheam, Worcester Park, Esher, Walton on Thames and Banstead. This antenna was installed by SBS for the then Thames FM. This aerial has now been replaced.... UPDATE: The Sira type antenna was removed in 2004 and replaced with a completely different type of aerial, which is now mounted at a different part of the building as Mike Craig explains: Hi Mike, I bumped into your site while searching for pictures of Valleys Radio's AM site. Thought I'd drop you a line about Radio Jackie's antenna on Tolworth tower, since I was involved with it's construction. [The new Radio Jackie antenna was made by] by Martin Spencer associates, and is slightly directional (2dB null); as required by Ofcom. The antenna was designed using computer antenna modelling software by Martin Spencer, and the manufacture of the loop antennas was carried out by myself. Construction of the system and testing of the entire array was carried out by me and Martin in Brighton prior to delivery. The vertical antenna is a Jaybeam, modified to be directional by the addition of a insulated vertical reflector rod attached to the mast by a 'hockey stick' mounting pole. The two horizontal loops are dimensionally adjusted to give the required directional pattern, and are of heavy duty construction, pretty much to mil spec! Two are required to reduce any high angle signal component (an Ofcom requirement), that can cause problems with 'mixing' in aircraft receivers. The power split between the antennas is handled by a splitter of our design. Our solution greatly improved Jackie's signal coverage and I understand they are very happy with the improvement! We have since supplied this antenna design to other customers. Hope you find this of interest! Best regards, Mike Craig. |