"Haines Brown" wrote in message
...
"Mike Kaliski" writes:

"Haines Brown" wrote in message
...
Automotive couplers for two metres manage with a 2 inch by 2 inch
plate either side of the glass. It could be worth trying 6 inch by 6
inch plates on the domestic window and see what signal level gets
out. Reception shouldn't be a problem if you can get 50% or more of
your transmission power out through the glass.

The suggestions for a panel to insert into a partially opened window and
to close the window on twin lead seem out. It's a steel casement type
window that must be fully shut, and even if twin-lead were to get around
the edge, it would be sandwiched in steel. I don't own the wall, so even
if a hole could be put in it (which it can't), I don't own it.

On the positive side, this is a single pain of ordinary class, and I
could make a capacitative coupler over 12" square and still get too near
the steel frame. It's a curtained window, and so appearance is not
important.

A question. Is this coupling purely capacitative at this frequency (the
more surface area the better), or is it somewhat tuned (try different
sizes to see what signal level gets out).

An obvious question, how can the coax be connected to the sheets of
metal? That is, what happens to the braid? Or could there be two sheets
next to each other on both sides of the glass, say one foot square each,
with one for the coax center conductor and one for its braid?

The only advantage that a commercial coupler might have is that the
visual asthetics might be a bit better than a home brewed effort.

I was hoping to see a commercial coupler to figure out how they are
constructed, but so far have seen only one for XP radio, and it is not
clear what's up with it.

--

Haines Brown, KB1GRM

Haines,

The versions I used years ago relied purely on capacitive coupling. The
braid was broken and only the centre lead of the coax was connected to the
plates. The earth return was via the automobile chassis for vehicle use, or
via earth connections for domestic use. The metal frame of the window might
work if you have any means of getting a good connection, otherwise you will
need some form of reliable (low impedence) earth connection inside and
outside the building for the system to work properly.

The coupling through the glass should be purely capacitive although some
inductance effects will inevitably be introduced due to the size of the
plates.

As an alternative you might consider making up two matched tuned circuits
(coil and capacitor) set for the 10 metre band and try inductively coupling
the coils through the glass. To my mind that would be smaller and easier to
set up without the need to worry about earth feeds. A kind of through glass
balun if you like. Obviously you will need to keep a reasonable distance
away from the metal window frame, but a couple of turns of wire and a
couple of capacitors may be all you need.

Mike G0ULI