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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
Rubens
PY2RML
DIAGRAM BELOW
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