How get RF through a sealed window?
 

Perhaps.

In an emergency situation though, you do what you need to do and try not to
let the regulations keep you from saving lives and/or property..while still
keeping the regs in mind.

When I use my portable mag loop for 20 and 40, from my hotel room, I try to
place it outside my room...but that hasn't always been possible. At my low
power I would have to guess the RF I'm bathing in should only be slightly
more harmful than the X rays leaking out of my cheap "Made in Turdistan" TV
set. I certainly wouldn't attempt using this setup with much more than a few
watts of power.

As for my attic dipoles, I have never tried to measure the exposure level in
my home. I'll check in to that..but again, at 5w or less it can't be too
dangerous.

73

--
=========================================
Radio Amateurs - Fill your junk box, from my junkbox!
http://www.hamradparts.com
73 de KB9BVN
=========================================


wrote in message ...
You'd have better luck with HF than VHF or UHF making it through any
solid
object. I have used a homebrew mag loop in a hotel room on several
ocassions with some luck..on 20 and 40.

Even in an emergency situation, I just don't think it would be a good idea
to string some kind of an antenna above the heads of shelterees and then
start soaking them with RF, especially depending on the HF frequency in
use. In fact, I suspect the FCC's RF-exposure regulations would frown on
one doing so!

--
--Myron A. Calhoun.
Five boxes preserve our freedoms: soap, ballot, witness, jury, and
cartridge
PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785)
539-4448
NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle,
Pistol)

How get RF through a sealed window?
 

But in emergency/expedient situations, it would be really handy if one
could pass at HF, say, 100 watts of RF energy through a window (I
visualize some foil strips and an inductor or two to "tune out" the
capacitance) to an external antenna.

What I have done is plan ahead by drilling two small holes in the glass
and plugging them with nylon screws when not in use. That works best
on the first floor. :-)
===============================
Might be OK for single - ,but NOT for double glazed windows.

A solution for HF 'might' be an inductive coupler/matching unit , with
half of it including an inductor on the outside with the other inductor
and 'tuning bits' inside .Both inductors 'in-line' for best possible
coupling. If an outside variable capacitor is to be used ,its shaft
could possibly be magnetically coupled with a manipulator fitted inside
,using strong magnets .
Home-brewing Ham Radio equipment is and remains an interesting
ideas-provoking activity .

Frank GM0CSZ / KN6WH

How get RF through a sealed window?
 

"Brian Murrey" wrote in message
ink.net...
In an emergency situation though, you do what you need to do and try not to
let the regulations keep you from saving lives and/or property..while still
keeping the regs in mind.

Slightly off-topic, but see: http://www.truck.net/showdetail/rec_id/1182.
Bizarre...

How get RF through a sealed window?
 

On 6 Apr 2006 11:06:22 -0500, wrote:

I gave a presentation on "How Ham Radio Can Help You in an Emergency"
to 70 Emergency Management types last week, and the windows in the
building which hosted the meeting were NOT open-able (so I "made do"
with an inside VHF antenna and didn't even try to demonstrate HF).

But in emergency/expedient situations, it would be really handy if one
could pass at HF, say, 100 watts of RF energy through a window (I
visualize some foil strips and an inductor or two to "tune out" the
capacitance) to an external antenna.

If the window is sealed, and on something other than the first floor,
how are you going to attach an antenna on the outside? It seems
getting RF through the glass might be the least of your problems.

If it's a hotel, ask for a balcony...

bob
k5qwg



I've been told that the April, 1989, issue of Ham Radio magazine carried
an article "Easy antenna access for urban apartment dwellers" (for 15
meters) by Bryan Bergeron, NU1N, starting on page 18.

I'd sure like to read that article; can anyone send me a copy?

How get RF through a sealed window?
 

wrote in message ...
I gave a presentation on "How Ham Radio Can Help You in an Emergency"
to 70 Emergency Management types last week, and the windows in the
building which hosted the meeting were NOT open-able (so I "made do"
with an inside VHF antenna and didn't even try to demonstrate HF).

But in emergency/expedient situations, it would be really handy if one
could pass at HF, say, 100 watts of RF energy through a window (I
visualize some foil strips and an inductor or two to "tune out" the
capacitance) to an external antenna.

I've been told that the April, 1989, issue of Ham Radio magazine carried
an article "Easy antenna access for urban apartment dwellers" (for 15
meters) by Bryan Bergeron, NU1N, starting on page 18.

I'd sure like to read that article; can anyone send me a copy?
--
--Myron A. Calhoun.
Five boxes preserve our freedoms: soap, ballot, witness, jury, and
cartridge
PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785)
539-4448
NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle,
Pistol)

I have drilled a hole in a window frame and passed a piece of RG-58 through
it. A 2M rig in my den is that way right now. It's easier to justify doing
it to your own home than to a place you're visiting

How get RF through a sealed window?
 

Myron,

I built a set of tuned rings to couple a 4MHz signal from an ultrasound
transducer to its processing/signal generation box. I used a small
copper ring (only about 6") split at one point with a resonating
capacitor across the gap on the ultrasound box side. The coax was
connected across this gap also.

On the transducer side, use an identical loop and capacitor but make a
series resonant circuit (capacitor in series with one of the feedline
leads). Loops were separated by about 1/4 inch.

I know this configuration (parallel resonant on the transciever side,
series resonant on the "antenna" side) worked the best.

It worked well in terms of passing the signal through undistorted
(looked at amplitude and phase on both sides of the circuit, only got a
bit of a phase shift, no amplitude loss)

I don't know about power handling. If you use hefty capacitors, there
should be no problem. Bandwidth could be quite low with high-Q
circuits, but maybe you could use variable caps.

I think your idea with capacitative coupling with inductors to tune out
the reactance would work fine too, but I haven't tried that.

Anyway, the inductive thing works OK. I got the idea from a older
(1950's?) ARRL antenna book that touted it as a way to allow rotation a
parallel-line fed beam.

You'd certainly need a set of coupling rings for each band of interest,
or switched or variable capacitors.

Low E glass would get some eddy currents going. I don't know how
conductive it really is though, so ... who knows?

73,
Dan
N3OX
www.n3ox.net

How get RF through a sealed window?