Re: [Phys-L] physics in the real world : WAN in a cage
I was going to reply in that manner, but couldn’t, because I hadn’t read
carefully enough to know it was a common radio phone transceiver. and my
testing of my radiophone was not working, i.e. goes directly to VM when I call
using my plastic and copper ’phone. BUT
now the radio ’phone answers. So in the microwave no go. in a metal paper
basket with my M2 air as cover does go (not covered well enough.?) With one
layer of aluminium foil goes; second layer no go. Hint to the tin hatters.
My reasoning grid spacing, so I’ve read, one tenth of wave length is good
enough. My experience is about half wavelength makes equivalent of half
silvered (Al of course) for interferometer splitter. [1] Since no geo. hammer
or ruler supplied in pic. No comment possible. As always (Well with rare
exception) JD supplied the answer.
bc …. too dim to notice polarization of antenna, and forgot his view of
transceiver antennae nearly next door.
p.s. the FCC supplies the spectra — noticed long ago his use of the 420 => 450
MHz gone. Which he used for communication in a v. large area CR shower
detector. Detail supplied on request.
[1] Yes, I’ve made one at X-band. But too long, for my incipient Alzheimer’s,
ago.
> On Sep 30, 2023, at 04:29, John Denker via Phys-l <phys-l@mail.phys-l.org>
> wrote:
>
>
> In more detail: Here's how I instantly knew it would be trouble: You
> can figure out the wavelength of the WAN system by looking at the
> antenna. You can guess that it's a 1/4 wave antenna. And in fact
> that's a very good guess; I checked that the device is primarily using
> the 700 MHz bands. Occasionally 600, and occasionally 850, but that
> doesn't change the conclusions.
>
> Now look at the grid spacing on the cage. It's tight compared to the
> wavelength. Then apply the Huygens construction. Conclude that as seen
> from the far field, a tight grid is indistinguishable from a solid
> slab of metal.