tuning a window frame
 

I suppose you could gamma match it.

--
Alec Wood M1BNK
Teesside UK

Interested in Ham Radio....have a look at www.ukradioamateur.org

"Ketalar" wrote in message
...
Subject to restrictions and poor location, I can't install any antenna.
My window has an aluminium frame.
I considered to use it as a loop, but it is inherently shorted.
How would you feed that ?
Freq : FM BC band.
Window : abt 0.90 * 1.60 (metres)
Thanks by advance.

Ketalar,
Assuming that the antenna would be for receiving only,
just connect a single wire between the receiver and the
window frame. Don't worry about 'matching'. And a second
wire from the radio's ground connection to ground. Will
there be an improvement in reception? Beats me! But it
shouldn't be difficult to find out...
'Doc

TNX fer the answer. That's what I was looking for, but I'm not an expert abt Gamma-matching : how should I proceed ?

Le Wed, 30 Jul 2003 13:07:39 +0100, Alexander S. Wood a écrit:

I suppose you could gamma match it.




--
A personne, sauf Ã* ceux qui y prendront plaisir (Franz Schubert, 1797-1828)

Subject to restrictions and poor location, I can't install any antenna.
My window has an aluminium frame.
I considered to use it as a loop, but it is inherently shorted.
How would you feed that ?
Freq : FM BC band.
Window : abt 0.90 * 1.60 (metres)
Thanks by adv

...........................................
Try connecting your leads (both) to various points on the window,you might get
lucky. I was able to achieve resonance with the windscreen
frame on a Sunbeam Tiger I restored. Luckily the spacing of the mounting studs
were close to the right tap points.
Works better the the usual 1/4 wave whip!
KC*VIF
Greg Z
to thine own sound be true

For instance, the distance between the two tap points : which one to start with , supposing I insert a variable capacitor (Sorry, the only antenna work I did was for top band) ??

Le Wed, 30 Jul 2003 18:38:09 +0200, ketalar a écrit:

TNX fer the answer. That's what I was looking for, but I'm not an expert abt Gamma-matching : how should I proceed ?

Le Wed, 30 Jul 2003 13:07:39 +0100, Alexander S. Wood a écrit:

I suppose you could gamma match it.







--
A personne, sauf Ã* ceux qui y prendront plaisir (Franz Schubert, 1797-1828)

But with the window open, or shut??
'Doc

I'll first try with the outer frame !
In summer I could turn (i.e. open) the window to see if there is an
improvement !

'Doc wrote in :



But with the window open, or shut??
'Doc

- Yes, that's only for receiving.
I need a decent signal for stereo, otherwise t is a bit noisy...
Coming back to the beginning of the discussion, I only wondered what
would be the approximate distance between the feedpoints (given the
size of the frame), and the capacitor range.
Gamma matching has always been a mystery for me....
Best regards to all,


On Fri, 01 Aug 2003 22:00:39 GMT, "Tim Conway"
wrote:

Incidentally, you do intend this as a receiver only, right?

thanks for the idea.
But I already tried this method : it does not work fine here : I'm between
concrete walls.

On Sat, 2 Aug 2003 05:28:21 -0400, WB3FUP (Mike Hall)
wrote:

For FM go to Radio Shack. Buy a folded dipole
(420-2385) for less than $5.00. Put it up as an
inverted V so that it is omni directional. Enjoy
your radio.




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On Sat, 02 Aug 2003 15:56:29 GMT, Richard Clark wrote:

Odd no one has actually answered your question.

- Maybe my poor english...

However, it pretty much depends on the physical dimensions of the
window frame (does the sash present a moving short across it?) before
a solid value would work. You also suffer a potential problem of it
pointing the wrong way to serve your needs (how would you tune it, if
it didn't hear anything?). Also, where you put the Gamma match would
also affect how it tuned up.

- No sash windows here in France ; they open (and close) like doors.
The window size is abt 0.90 * 1.60 (metres), which makes a gross 1.7 wave,
not so far from a 2 wavelenghts closed loop, like a square in a circle...
I suppose I could try to space my croc clips a quarter wave apart ??

Another point, if you just made the match a little longer, threw away
the capacitor, and screwed it to the wall instead; then it would
probably do just as well.
Hint: you may solve your problem more with height (put a simple
dipole up higher) than with tuning.

- You mean tap on top of the frame ?

73's
Richard Clark, KB7QHC

- Tnx es ame to you de F5LCI




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