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      The future of the JD Forum   07/31/18

      Thank you all for your participation on the JD Forums.  We have enjoyed answering your questions, providing project advice and technical assistance on this forum for a number of years. We believe that there are now better ways to provide this service for our customers and the community. With that in mind, we have made the difficult decision to discontinue the Jamestown Distributors Forum.   Our JD Tech Team is committed to being your trusted technical resource, and we encourage you to reach out via email, phone, social, product reviews, and to post questions using the Q & A 'Ask A Question' function on all product pages. Additional information can also be found on product page Technical Data Sheets (including detailed usage instructions and application data).   Thank You Jamestown Distributors 
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Antenna Height

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For line of sight transmission such as VHF radios, antenna height is paramount. Mounting an antenna of adequate length at the best possible height assures the furthest range along the curvature of Earth. (Information based on Geographic Range Table calculations in Coast Pilot. i.e. 5 ft above sea level has line of sight of 2.6nm, 10 ft height has a range of 3.7nm.) As a general rule, sailboats typically mount a 3-5ft antenna on top of the mast. This mounting elevation offers superior range of communication. Racing sailboats sometimes opt to mount an 8 ft antenna on the stern as a fail safe against dismasting at sea. Powerboats up to 25 feet in length typically install a standard 8 ft antenna, while bigger vessels may require a larger antenna with higher gain. The other limiting range factor is power of transmission, but standard radios are most often limited by geographic range before power becomes a consideration. In US waters, transmission power is also regulated by the FCC.

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