Hey Vinnie............I can help you. The formula for a 1/4 wavelength
radiator is (234 / F) whereby F is the frequency in MHz. This will give you
the length in feet. For the radials, (237 / F) will give you that length.
Always remember...multiply the radiator length by 1.05 and that is another
way of calculating the 1/4 wavelength radials.
The feedpoint impedance of a 1/4 wave ground plane is 37 ohms when you have
the radials at a 90 degree angle with respect to the radiator. If you have
the radials drooped at a 45 degree angle, the impedance rises to
approximately 50 ohms.
If you have a single radial drooped at a 180 degree angle with respect to
the radiator, the impedance rises to 75 ohms.
There was an article in RF Design magazine a few years back, explaining why
certain impedances are used in the RF industry.
72 ohms was the impedance that produced minimum cable losses...........50
ohms is a happy medium.
On a final note...........at 37 ohms, you will have a VSWR of 1.3 to
1.................at 75 ohms, you will have a VSWR of
1.5 to 1. What is the difference here? For a transmitter with a tube output
and an internal matching network, you wouldn't really see much effect. For a
typical solid state transmitter, there would be some difference between the
two antenna impedances, because the broadband solid state transmitter would
be called upon to deliver more current to the antenna. It probably wouldn't
have any effect, unless the ALC circuit was aggressive in its operation. In
this case, power foldback would occur into the 37 ohm load. Would it happen?
Probably not.
I hope this helps.

Pete

"Frank Gilliland" wrote in message
...
On Wed, 06 Apr 2005 20:14:16 -0400, Vinnie S.
wrote in :

On Wed, 06 Apr 2005 17:15:08 GMT, Lancer wrote:


Why should I be nice? I -was- nice. We have had civil converstations,
and I even gave him enough info to install the antenna in his attic,
which apparently worked quite well. Then he stuck his finger into the
political lion cage and turned into a sniveling crybaby after getting
scratched.

As for being a general-class amateur, there are literally hundreds of
hammie websites that cover nothing but antennas, not to mention the
ARRL manual. If he's so serious about radio, why beg a CB group for
info on how to install a prefab antenna? J.H.F.C, how did he pass the
exam without knowing a few antenna fundamentals? And if part of the
hobby is to learn about radio comm, why ask a CB group for tech info
when there are countless resources available for hams? Isn't anyone
elmering the kid?




I thought your were elmering him Frank?

He really doesn't need one anyway, he buys his antennas. Even
something as simple as a dipole, or sloper...


Do you have a problem with that? Show me the rules on antenna
requirements,
please.


Looks like Vinnie is going to be a General-class appliance operator.






----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet
News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+
Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption
=----