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Re: [TowerTalk] RF Ground is not a Myth

To: towertalk@contesting.com
Subject: Re: [TowerTalk] RF Ground is not a Myth
From: Patrick Greenlee <patrick_g@windstream.net>
Date: Sun, 25 Jan 2015 07:23:57 -0600
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Holy Cow!!! Welcome to Lilliput. Didn't a lot of us start out with the water analogy to understand simple electrical circuits. In my first formal electronics studies we used hypothetical components: pure resistances, perfectly conducting wires, idealized capacitors and inductors and then later had radiators over perfectly conducting planes of infinite dimension. Different levels of detail and "reality" are appropriate for different purposes.

So someone treats a simple wall switch as an on off device and someone else has to complain because he didn't allow for its inductance, capacitance, radiated energy, damped oscillation from the little arcing, and on and on. Sometimes a switch can be just an idealized on off device with little consequence with respect to the actions of the device that switch energized.

Which end of the boiled egg do you break open, i.e. who do you support in this war of the Lilliputians? Quoting Rodney King, "Can't we all just get along?" We don't have to agree with one another to be civil. I, for one, learn from the interchange of ideas and technical challenges we pose to each other but lets keep it above the level of a street fight, OK?

Patrick    NJ5G

On 1/23/2015 5:20 PM, Steve Maki wrote:
I was flabbergasted at the response to Duffy's post, which seemed relatively non controversial to this relatively low level scientific brain of mine. Can't one specify a perfect ground (even though impossible in the real world) when modeling antennas? Is that not a useful exercise as an educational tool? Does that not prove his point?

-Steve K8LX

On 1/23/2015 4:32 PM, Wes Attaway (N5WA) wrote:

"Believing in something does not make it so" .... Really?

What about an isotropic radiator, defined as a theoretical point source, as
used in every antenna modeling program?

What about the "imaginary numbers" which consistently pop up in mathematical
analyses?

The author (Bryan Fields) was careful to point why the use of something that
is not physically realizable is still useful (even required) in certain
kinds of analyses.

I think he made a perfectly valid argument about why the concept of an RF
Ground is important, as he says "in understanding current flow in RF
circuits".


    -------------------
Wes Attaway (N5WA)
(318) 393-3289 - Shreveport, LA
Computer/Cellphone Forensics
EnCase Certified Examiner
    -------------------
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Bryan
Fields
Sent: Thursday, January 22, 2015 11:52 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] RF Ground is not a Myth

On 1/19/15, 9:29 PM, James Duffey wrote:
The RF ground is a useful theoretical construct. This theoretical
construct
is a result of solid thinking.

Believing in something does not make it so.

Given that it is hard to realize in
practice, but it does have its use in understanding current flow in RF
circuits, the practical problems in implementing a useful ground, and why
we have problems in circuits that we don't think should have problems.
Simply put, an RF ground is an infinite source or sink of carriers,
delivered or received with minimal delay. That of course is not
realizable,
but understanding why the carriers cannot be delivered or absorbed with
minimal delay helps a great deal in understanding the practical
implementation of circuits we design.

Literally nothing is correct in that paragraph.


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