Re: DIY WiFi antenna (to increase reception)

From: Stan Goodman (SPAM_FOILER_at_hashkedim.com)
Date: 06/11/05 

Date: 11 Jun 2005 20:55:07 GMT

On Sat, 11 Jun 2005 19:51:14 UTC, James Knott <james.knott@rogers.com>
opined:
> Stan Goodman wrote:
>
> > What sort of house do you live in? Mine is a single storey structure made
> > of concrete blocks, with a metal-screen lathe and plaster ceiling under a
> > tile roof. Is yours like that? Or is it a frame structure? These walls are
> > made of what? Gypsum board? That would sound to me like not much of a
> > block to the passage of a signal at these wavelengths; it would sound like
> > they are fairly transparent. "Transparent" means they don't exist, from
> > the point of view of line of sight. The fact that, not having been born on
> > the planet Krypton, you can't see them doesn't change that.
>
> I live in a condo, with concrete between me and the garage. Also concrete
> between the stairs and garage.
> >
> > If the walls are concrete, and the signal "passes through them" as you
> > say, then by definition they are transparent, and the same reasoning
> > applies. Are they two feet thick?
>
> I used the term "relatively", in that the signal passes through those
> materials, with some unknown degree of attenuation. Different materials
> have different amounts of attenuation of radio signals passing through
> them. A signal passing through concrete or drywall will be more
> attenuated, than if passed through air or vacuum.
>
> >
> > Anything that the signal "passes through", to repeat, is transparent, and
> > meaningless for line of sight. Line of sight doesn't require "free air".
> > If that were not true, your glass or plastic spectacles would be
> > interfering with the line of sight to your breakfast coffee and the
> > newspaper.
>
> Ever hear of loss in fibre optic cable? The glass used in it is far more
> transparent than window glass, so it produces less signal attenuation.
> However, if you have enough of it, it becomes opaque to the signal. There
> is measurable loss in any substance you care to mention. A truly
> transparent medium would have no loss whatsoever attributable to that
> medium. The only thing that applies to, as far as I know, is a vacuum. We
> don't notice the signal loss in spectacles, because they're fairly thin.
> If they were a few meters thick, there wouldn't be anywhere near as much
> light coming through them.
>
> Incidentally, on a related topic: The U.S. nuclear navy is a result of the
> work done by Adm. Hiram Rickover. Due to certain technical constraints, in
> a sub designed for espionage, they omitted the lead shield, to the rear of
> the reactor and instead flooded the compartment with water. The 13 feet of
> water provided equivalent shielding to 1 foot of lead.

I am not sure that you have added anything to what I said. 

-- 
Stan Goodman
Qiryat Tiv'on
Israel

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