Hey, thanks Ray, I guess I was close anyway.

Mike


From: Raymond Fink <justafink@...>
Date: 2007/12/07 Fri AM 11:05:42 CST
To: cbradio@yahoogroups.com
Subject: Re: [cbradio] 8'8" Dipole?


Ok, I did the calcs on the 8' 8" diapole and that thing will center
at 27.02mhz, very close to channel 2. Usually the idea is to center
your antenna in the middle of the frequency range you expect to
transmit. Most would opt for an antenna for CB use to be centered at
channel 20 (27.205mhz). The length for each radiator on a diapole at
this frequency would be roughly 8' 7". If you have a tendency toward
the upper channels, you may want to clip an inch off each end to
lower your SWR toward the higher frequencies. Higher the frequency,
the shorter the antenna.

For all who are interested, here's a handy calc to keep around: 468
divided by frequency = length in feet of a 1/2 wavelength radiator.
468 / 27.205 = 17.2 feet. Divide that by two (8.6 feet) and multiply
the number below the decimal by 12 (inches in a foot) to get the
number of inches. .6 times 12 = 7.2 inches. Roughly 8' 7-1/4" for
each side of the diapole will net a 1/2 wave diapole. I take the
easy route and cut one wire at 1/2 wavelength (17' 2.4"), then cut
that wire in two. Job done. Now you can thread it through some 3/4"
PVC pipe with a tee in the middle and it'll support itself.

Happy oscillating!

Ray

On Nov 29, 2007, at 11:55 AM, chingaling3 wrote:

> I've recently gotten back into CB/SSB'ing. Things have changed for
> sure.
> My topic is dipole antennas for CB. Back in the 1960's, when I was a
> kid, we all had radios and were very much into building longwire and
> dipole antennas. I distinctly remember that the recomended length for
> a CB dipole was 8 feet 8 inches on both sides, with one side connected
> to the center wire of the coax and the other side connected to the
> shield.
> However, nowadays I can't find anything on the internet to support
> those demensions. I did recently construct just such a dipole, as
> described above and it works really well.
> Any comments? Has anybody ever heard of the 8'8" dipole?
>
> Mike Bisbano
> Hampton, New Hampshire, USA 03842
> mjbiz@...
>
>
>

[Non-text portions of this message have been removed]




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