Hi Gentlemen,
This isn't exactly tower talk...maybe close enough...
I have tried several methods to measure *resonance* of a
vertical 20m antenna (which will become a multiband
trap vertical).
In tuning a antenna, I consider resonance and impedance
two separate subjects. Lowest SWR to me doesn't mean
"resonance". At this point in testing I don't really care
about the "input" impedance at the coax connector...the
antenna will be matched to the line later.
I have made many measurements using a GDO and a
MFJ 259-B analyzer and I get different readings of
resonance depending on what method I use to couple
RF to the antenna. When I used the GDO, the frequency
was monitored with a frequency counter of known accuracy.
I'm thinking that the lowest "X" (reactance) indication
on the 259-B would be THE resonant frequency, and
that I should connect the instrument with the shortest
possible leads (like a double-male coax connector)
to the "input" of the antenna. Is this correct? Or what
IS the best way?
BTW, the "X" reading has been 6 to 7 ohms with the
259-B and "X" will read zero when the 259-B is
terminated with a 50 ohm load.
73,
Charlie, N0TT
________________________________________________________________
GET INTERNET ACCESS FROM JUNO!
Juno offers FREE or PREMIUM Internet access for less!
Join Juno today! For your FREE software, visit:
http://dl.www.juno.com/get/tagj.
List Sponsored by AN Wireless: AN Wireless handles Rohn tower systems,
Trylon Titan towers, coax, hardline and more. Also check out our self
supporting towers up to 96 feet for under $1500!! http://www.anwireless.com
-----
FAQ on WWW: http://www.contesting.com/FAQ/towertalk
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
|