[JN] FUM ants...

Ian McPhail mrea2799 at bigpond.net.au
Tue Dec 1 20:06:47 CST 2009


Dudes, over here in Oz I love your net archives of www.wfmu.org 
Music to Spazz By is fun, fun, fun!
www.wfmu.org/playlists/MS tune in!
NPR is excellent too
www.npr.org

regards Ian

-----Original Message-----
From: sound-bounces at mailman.soundlist.org [mailto:sound-bounces at mailman.soundlist.org] On
Behalf Of bear
Sent: Wednesday, 2 December 2009 9:56 AM
To: sound at mailman.soundlist.org
Subject: [JN] FUM ants...

>
> Message: 6
> Date: Sun, 29 Nov 2009 22:15:45 -0500
> From: Daniel Normolle <dnormolle at att.net>
> Subject: [JN] FM Antenna
> To: Joe List <sound at lists.io.com>

>
> Hello, All,
>
> I have a new, hopefully temporary, apartmental life in Pittsburgh!  FM
> reception
> is TERRIBLE here, because of the hills and the building itself, I suppose.
>  I am
> thinking about an indoor FM antenna.  I have several commercial units, but
> they
> are no better than the usual 300-ohm T.
>
> Please take a look at this:
>
> 	http://www.ham-radio.com/k6sti/cpquad.htm
>
> In the top diagram, the loop that sits in back and to the right--I think
> that's the
> "reflector."  It's not connected to the other loop, which is the "driven"
> loop, right?
> It's just an independent square that sits 23 3/16" back from the double
> loop?
>
> Thanks!
>
> dpn
>
> PS:  Are there any Joes in Pittsburgh?
>
>

The Quad is a good ant.

Inside it will not perform as well as outside.
It is very unidirectional (cardiod, high front to back ratio)
You can merely stack on elements in *front* of the "driven element" (the
one with the coax connected).
He is likely showing a reflector and a driven element.
Elements in front (smaller size) than the driven element are called
directors. You can add in quite a number, the beam width gets narrower,
the front to back increases, as does the gain.

You can build it with wood - dowels or flats, varnish well. metal boom is
ok.

You can put it outside if you wish.

but you can also build a yagi.
Actually most old TV ants will do the dirty deed as well, the band was
split between ch5 and 6, ch 6 being smack dab at the bottom of the FM
band, so you can dispense with all the elements that worked below, and
most the the elements that worked above, in the case of a bigger than
needed old tv ant... an old three or 4 element TV ant will also work...

Joe's vertical will work ok. A 5/8th wave vertical will have some gain
too... ground plane is a bonus if you can get it (metal railing is nice)
or a counterpoise (same size wire as the wavelength of the ant, dropped
down aiming at the ground). But then it looks like a vertical dipole...
:-)

Which ant to use depends a bunch on the specific situation you have. Metal
siding or metal studs and you can forget about any indoor solutions...

Sometimes a random "long wire" made from thin thin wire (magnet wire has
been used, btw), but a strong steel wire being nice, being outside and
stretching some length will grab enough signal to do the job... you just
"launch it" with something that has some mass, use fishing line, then pull
the wire out, tie off the fishing line.

You didn't say what floor ur on, lower is more badder. So if you can throw
a long wire (invisible) up over a tree, ur going to do far better than
anything down at ground level possibly can.

              _-_-
_-_-bear

http://www.bearlabs.com
BEAR Labs

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