Topband: EZNEC 5.0 +

[Charlie Cunningham]

Thanks, Carl

I suppose all those wires helped to increase bandwidth.

Charlie
K4OTV

-----Original Message-----
From: Carl [mailto:km1h at jeremy.qozzy.com] 
Sent: Saturday, December 06, 2014 10:20 AM
To: Charlie Cunningham; 'Paul Christensen'; 'topband'
Subject: Re: Topband: EZNEC 5.0 +

Charlie, visualize a straight horizontal wire wire between two tall points; then slanting to vertical wires coming down to the common feed point.

The Titanic had a multi wire T horizontal and vertical fed in the center. 
Considering its daytime range of 200-400 miles and up to 2200 at night with about 500W radiated from a 5KW spark it was pretty effective on 600M.

Carl
KM1H


----- Original Message -----
From: "Charlie Cunningham" <charlie-cunningham at nc.rr.com>
To: "'Paul Christensen'" <w9ac at arrl.net>; "'topband'" 
<topband at contesting.com>
Sent: Saturday, December 06, 2014 12:41 AM
Subject: Re: Topband: EZNEC 5.0 +


> 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.
>
> 73,
> Charlie, K4OTV
>
>
> -----Original Message-----
> From: Topband [mailto:topband-bounces at contesting.com] On Behalf Of Paul 
> Christensen
> 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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