man N3OX
Date: Wednesday, April 27, 2011 9:43 am
Subject: Re: Topband: 160 metre vertical with 'top loading'
To: topband
> I made a plot this evening that might be of some interest. It > started
> with
> an EZNEC model (pretty sure one that originated with W5DXP) of a
&g
> A current decrease (meaning less current at one end that at the other)
> is not a loss, and it's far from being unexplained.
A good starting point is here. Specifically, scroll down to: "Why the Net
Current is not Constant Through a Loading Coil?"
http://www.w5dxp.com/current.htm
It's easy t
On 4/26/2011 1:49 AM, Tom Boucher wrote:
> I take your point Yuri, but my simplistic way of looking at the current
> decreasing along a straight quarter wave of wire is due to the current flow
> through it's distributed capacitance to ground. Maybe that is wrong and I
> should go back and look a
"Joe Subich, W4TV" wrote:
> Any coil that shows a 60% decrease in current through
> it has a significant amount of unexplained loss.
A current decrease (meaning less current at one end that at the other)
is not a loss, and it's far from being unexplained.
It's caused by the standing wave, jus
I made a plot this evening that might be of some interest. It started with
an EZNEC model (pretty sure one that originated with W5DXP) of a loaded
antenna that shows a clear, large current taper. There's only about half
the current at the top of the coil as at the bottom. The antenna is an
eig
> My main concern was to set the record straight about the current
> distribution in loading coil, that it is not equal (or some 3%
> variance) as some claimed, but more like 40 - 60%. Measurements
> prove that in mobile antenna shootouts.
"Mobile antenna shootouts" are about as much like rea
It would be of some considerable use to know exactly what you
summarize in saying:
On Tue, Apr 26, 2011 at 9:28 PM, wrote:
> I tried to use toroid as loading inductance, but it did not work well.
I can guess what didn't work well, but I would rather hear your details.
73, Guy.
W4EF writes:
> I agree. Clearly the current can vary a long the length of an
> air-wound
> inductor. If it didn't vary at all, then a helically wound
> vertical
> antenna element would not have a current taper. I don't think
> that has
> ever been in question. I think the real question that
W4EF writes:
My suspicion is that some taper does occur in air wound loading coils at
> HF frequencies, but that the amount of taper doesn't follow the simple
> rule that it equals the amount of taper that would occur in the length
> of straight radiator replaced by the inductor. I think the degre
- Original Message -
From: "Michael Tope"
To:
Sent: Tuesday, April 26, 2011 2:33 AM
Subject: Re: Topband: 160 metre vertical with 'top loading'
> On 4/25/2011 7:08 PM, k...@optimum.net wrote:
>> I do not want to start the argument all over again. One wo
I take your point Yuri, but my simplistic way of looking at the current
decreasing along a straight quarter wave of wire is due to the current flow
through it's distributed capacitance to ground. Maybe that is wrong and I
should go back and look at my transmission line theory.
Surely the fact
On 4/25/2011 7:08 PM, k...@optimum.net wrote:
> I do not want to start the argument all over again. One would expect people
> to read the material or argument carefully, trying to understand it and
> comment aproprietly.
>
> Just to set the record straight:
> It is not my famous picture but Barry
I do not want to start the argument all over again. One would expect people to
read the material or argument carefully, trying to understand it and comment
aproprietly.
Just to set the record straight:
It is not my famous picture but Barry's, W9UCW. He set up real life situation
and I was pleas
I think it would be good to do Yuri's famous picture with a coil of
identical inductance, but that is evenly wound around a T300A-2 iron
powder toroid, or the smallest that can create the inductance.
I don't think the actuality is nearly as simple as the opposite
arguments. If the coil is spread
> W8JI is correct in that the current into a perfect inductor must equal the
> current out of it.
Perfectly true.
> It's a piece of coiled wire so where else can the current go?
Wait a minute, a piece of coiled wire is not a perfect inductor!
It's a completely different beast: the perfect i
> On the eternally recurring argument about current into and out
> of a loading coil, here is the way my simple mind has always
> understood it:
>
> W8JI is correct in that the current into a perfect inductor must
> equal the current out of it. It's a piece of coiled wire so
> where else can
On the eternally recurring argument about current into and out of a loading
coil, here is the way my simple mind has always understood it:
W8JI is correct in that the current into a perfect inductor must equal the
current out of it. It's a piece of coiled wire so where else can the current
go?
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