Topband
[Top] [All Lists]

Topband: A little assistance needed with an attempt at a T antenna

To: "topband@contesting.com" <topband@contesting.com>
Subject: Topband: A little assistance needed with an attempt at a T antenna
From: Mike Armstrong <armstrmj@aol.com>
Date: Fri, 4 Jan 2013 06:56:07 -0700
List-post: <topband@contesting.com">mailto:topband@contesting.com>
Hey guys and gals,
I have a question: I have an OCFD that is about 130 feet long, end to end.  It 
is Off Center Fed at a current node for 15 meters, which is the band it was 
designed for.  Ends up that it tunes easy on just about any band, albeit with 
open wire feeders and a tuner.  It works very well for 10, 15, 17 and 20, since 
the major lobes are directed where I want them.  Although anecdotal, what I can 
say is that I rarely have to make a second call to any station I want to work 
on those bands..... which was a very real surprise considering its simplicity.  
it is 40 feet high, which is not great, but it is as good as I can do.  I have 
actually tuned it to 160 during a contest last year and ended up working (and 
thank you guys, CONFIRMING) a total of 9 countries....... Japan, Australia and 
Chile included..... Which REALLY blew my mind.  But I digress...... Suffice it 
to say that for the higher bands, I am very happy with it.

I want to try to use it as a T antenna and lay out some radials.  I do have a 
limited space situation, from a 160 point of view, with the typical postage 
stamp lot.  I got the OCFD as long as it is by placing a good portion of the 
antenna in my Mother-in-Law's property and terminating the far end in one of 
her palm trees.  I needed to say that because some folks might wonder how I put 
a long antenna on a postage stamp lot..... I didn't..... It is 2 postage stamps 
side by side.  However I can't go crazy and lay antennas everywhere on her 
land.  So...... After all the preliminaries, I want to try the T, but it 
definitely struck me that the antenna, being OCFD as much as it is, is 
definitely NOT balanced side to side.  Would this have a negative impact on a 
T?  Would it be better to call it an inverted L and just forget the short side, 
including that side of the transmission line?  I am thinking that the latter is 
probably the way to go, but if a T would work in such a strange c
 onfiguration, I would prefer to use the extra wire rather than having it sit 
idle.... LOL. 

Anyway, thanks for taking the time to read this tome..... Any response would be 
welcome, especially if anyone has actually done something similar with an OCFD 
that is so "unbalanced."  Ay anecdotal data concerning performance is welcome, 
as well...... If you are still using it, because it is a decent performer on 
160, that matters because you guys are so willing to alter antennas if they 
aren't doing EXACTLY what you want them to...... He he he.

Mike AB7ZU

Kuhi no ka lima, hele no ka maka
_______________________________________________
Stew Perry Topband Distance Challenge coming on December 29th.

<Prev in Thread] Current Thread [Next in Thread>