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10 Meter Dipole Project Using The Velocity Factor of Coaxial Cable
To Reduce the Size Of Antennas
(Project was taken and edited with permission from Rubens, PY2RML, Brazil)
Hi N4UJW, Hamuniverse.com and all,
I invite you the try on the air my new coaxial antenna for 10 meters.
(a simple dipole)
It is made using the .66 velocity factor of RG58, based on the project page http://www.hamuniverse.com/K4mmg2and6meter.html
Using this idea, the antenna is shortened 30 to 40 percent less than the standard dipole!
See detail picture at bottom of article.
The math and construction is very simple!
This antenna can be designed for the lower hf bands to greatly reduce the overall size versus the standard dipole type for those who have limited space for low band antennas.
Each side of the dipole is .66*[(300/28.450)/4] = meters for one half of the antenna..
I use a RG58 foam (celular type).
The same math above in a more simple form:
.66 X 75 / 28.450mhz = meters in length per side (We eliminate the extra division step by 4)
Result is 1.73 meters per side = 5.67 feet when converted and 11.34 feet total span.
The standard dipole formula 468/freqmhz would give us an antenna 16.44 feet long total! Use the handy calculators and coversion tables here to convert from metric.
This is about 31 percent longer!
Or said in another way...using the velocity factor gives us an antenna 31 percent shorter!!!!
The antenna is 4 meters above ground, horizontal polarization.
About the supports:
I always use Nylon 0.8mm for my dipole supports.
It´s cheap, light, and easy to elevate my experimental
antennas, that I put up and down ten times a day!
I had a perfect match with my RG58 cable to the rig.
It was a 1: 1.1 SWR in the first test mounted up about 13 feet.
Today I had QSOs with Bulgaria, Italia, Morrocos and the USA.
I´m in Southern Brazil.
Really nice idea!
I´m still experimenting with it.
Hope to make a QSO with you soon!
Thanks for the page ! 73
PY2RML DIAGRAM BELOW
Disclaimer From the Editor: All information on this page represents the author's opinion, experiences or results, based on his background, or experience with the particular subject in good faith. This does not necessary imply that the provided information has been substantiated by actual theory if needed, depending on the article content, and in no way intended to discredit actual theory. It should only be regarded as an outlet for him to publish his desire to share his thoughts, experience, methods, results, performance, or his ideas with you for your information if you choose to use it for reference.
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