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Re: Topband: EZNEC 5.0 +

To: "'Paul Christensen'" <>, "'topband'" <>
Subject: Re: Topband: EZNEC 5.0 +
From: "Charlie Cunningham" <>
Date: Sat, 6 Dec 2014 00:41:01 -0500
List-post: <">>
Not sure that I can picture just what you are describing, Paul. Even though, I 
wasn't born until 1944, I've explored just about every type of antenna and I've 
modeled an awful lot of them.

Of course the typical inverted L is just a monopole that is bent over at the 
top to reduce the required support height, and an inverted L with elevated 
radials is just a ground-plane antenna that is bent over at the top and the Tee 
equivalents just replace the single top wire with equal and opposite wires at 
the top to extend the monopole to resonant length. The Tee version does 
eliminate the modest residual horizontal component in the far field that occurs 
with the inverted L configuration. Of course antenna current is still 
fundamentally important - that's what does the radiation!  I do still have a 
matched pair of RF ammeters around here, but these days we accomplish the 
equivalent measurement by measuring forward power with our SWR bridges.  
There's still a fundamental I-squared x R relation between power and antenna 
current, where R is the radiation resistance of the antenna + copper losses.  
So, it's all the same thing, really. I can't come up with the name of the 
antenna that you are describing, because I can't quite picture it.

Charlie, K4OTV

-----Original Message-----
From: Topband [] On Behalf Of Paul 
Sent: Friday, December 05, 2014 11:23 PM
To: topband
Subject: Re: Topband: EZNEC 5.0 +

> "What did they call the teens to 20's antenna that had multiple feeds 
> coming
down from one end of the flatop to the other?"

Both the "T" and the fanned inverted L were popular on 200m in 1910-1920 just 
as the single-wire Inverted L is today on 160m.  Back then, ops were obsessed 
with maximum antenna current but radiation resistance didn’t enter into the 
discussions until the mid '20s.  By the mid 20s when CW took over, much less 
attention was paid to antenna current as a station performance metric.

During the spark era, ops would keep adding horizontal wires to the flat top 
fans until the line current reached diminishing returns.  We typically see 
5-6 wires wide-spread in old station photos.    Then, separate wires would 
connect to the flat top and extended down a common point where it became a 
single-wire feeder.

Paul, W9AC 

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