[TowerTalk] Length of Inverted-L.

[Wes Attaway (N5WA)]

Pete:

I think the main reason to adjust the length of an Inverted-L antenna is to
move the point of resonance, i.e. to get the point of lowest SWR where you
want it within the band.

You can model the antenna and check the differences in pattern, which should
be slight with the length variations you are talking about.

As you know, there are a number of things that can affect the pattern and
SWR of a vertical.  My experience has been that with an inverted-L it is
best to start with the top leg slightly long and trim down to where you want
the lowest SWR to be in the band.

Everyone's situation is different and in some situations you may have to
vary the vertical length due to being constricted as to how long you can
make the horizontal leg.

I have used a variety of inverted-L configurations in years past and they
all seemed to work pretty well as long as I had plenty of radials laid out.
I don't think there is much "magic" in trying to escape the ground aspect if
you expect to have good low band performance.

   -------------------
Wes Attaway (N5WA)
(318) 393-3289 - Shreveport, LA
Computer/Cellphone Forensics
AttawayForensics.com
   -------------------
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of N4ZR
Sent: Friday, October 05, 2018 10:12 AM
To: TowerTalk
Subject: [TowerTalk] Length of Inverted-L.

What to do when two respected references differ?  ON4UN's book assumes 
an Inverted-L is always a quarter wave ~135 feet), while the ARRL 
Antenna Book assumes 165-170 feet.  ON4UN mentions longer antennas to 
increase feedpoint impedance, but doesn't seem to put much faith in that.

Comments?

-- 

73, Pete N4ZR
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