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2 METER 1/2-WAVE J-POLE
VHF-FM Antenna Made From 450-Ohm LADDER LINE
Great first time J-pole project.  Covers most of the basics.
This small and thin design also makes it good for several stealth applications.
And......We've nicknamed this design the "LL-Coool-J"

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Comments section

 


Reminder: Always ID your station when testing... 
Technical Data: Ref.:V1.02; ID:LL-coool-j; Dated:08/04/03
Velocity Factors Estimated:
Open Wire@ 98% (insulation removed; as used in upper element section)
Insulated 450-Ohm Ladder Line@ 92% (as used in lower matching section)
Element Length Predictions:
1/2 Wavelength @ 98% = 39.63" +/- 1%  (146.000MHz @ 40.44" in free space)
1/4 Wavelength @ 92% = 18.60" +/- 1%  (146.000MHz @ 20.22" in free space)
Lower Folded 1/2 Wave Matching Section = 1/4 Wavelength in this calculation

 
More information to help you build this J-pole antenna for other frequencies:
5/8 Wavelength Formulas:
"615" divided by the frequency in Megahertz (this # is in feet)
(and multiplied by 12 inches) = the free space 5/8 Wavelength in inches
(and then multiplied by the Velocity Factor %) = electrical 5/8 Wavelength in inches
or
615/MHz x 12 x VF = electrical 5/8 Wavelength in inches
1/2 Wavelength Formulas:
"492" divided by the frequency in Megahertz (this # is in feet)
(and multiplied by 12 inches) = the free space 1/2 Wavelength in inches
(and then multiplied by the Velocity Factor %) = electrical 1/2 Wavelength in inches
or
492/MHz x 12 x  VF = electrical 1/2 Wavelength in inches
1/4 Wavelength Formulas:
"246" divided by the frequency in Megahertz (this # is in feet)
(and multiplied by 12 inches) = the free space 1/4 Wavelength in inches
(and then multiplied by the Velocity Factor % ) = electrical 1/4 Wavelength in inches
 or
246/MHz x 12 x VF = electrical 1/4 Wavelength in inches
Editor's Notice:

Please check out N4UJW's "Hamuniverse.com": http://www.hamuniverse.com
Don N4UJW has a lot of great antenna projects information..
All kinds of interesting and unique ideas!  Stuff you won't find anywhere else..  Just great information!!
Also, see the page Don set up about this antenna design: http://www.hamuniverse.com/2mladjpole.html
Thank you very much Don for all the work you do for the hobby!!

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