Tuesday, July 31, 2012

Simple Antennas for Amateur Radio Operators--a continuing series

KH6JRM's Amateur Radio Blog

Post #177

A modified fan dipole

How would you like to make a simple, stealthy, and inexpensive antenna that covers 80 to 10 meters?  All you need is a local hardware store, some connectors, some RG-8 coax, schedule 40 pvc pipe, some copper plumbing straps, a few bungie cords, and about 250-feet of stranded copper wire.

The details of this fascinating skyhook can be found in the 31 July 2012 edition of eham.net (http://www.eham.net).  Howard Gorman, W6HDG, has writen an article entitled "The Fence Fan Dipole (FFD)--A Quick, Easy, and Inexpensive Multiband Antenna."

Howard provides detailed instructions and photographs to guide you in completing this project.  Most of the materials for his antenna came from a local Home Depot store.  Howard used a 12-foot fence around an old tennis court to support a 10-foot schedule 40 pvc pipe and ran antenna elements from a special antenna connector atop the pvc pipe.  He used bungee cords to attach the elements for each band.  The antennal elements also served as guy wires for the pvc pipe.  He fed the antenna with one piece of RG-8 coaxial cable.  Howard's station is modest--a Yaesu FT-857, an Astron 30-amp power supply, and an antenna tuner.

According to Howard, SWR readings for all bands except 15 meters showed SWR at 1.9 or less across each band.  Fifteen meters and portions of 75 meters could be used if an antenna tuner were used to reduce the SWR.

Howard acknowledges the limitations of his creation by noting, "I have no illusions about DX worthiness of this antenna.  The multiband variety of dipole...when well-tuned, should not suffer appreciably in performance over a monoband dipole at similar height.  The advantage of  a single feedline connot be overemphasized."

Despite the limitations of this antenna, it's worth a try, especially if you don't have much real estate to erect antennas.  Howard says the antenna is barely noticeable and blends in well with the environment--something to consider in crowded neighborhoods.  If you follow Howard's instructions and photographs, you should have little difficulty in building and using this antenna.

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Aloha es 73 de KH6JRM--BK29jx15