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Re: [Discuss-gnuradio] Looking for more antenna details
From: |
Eric Blossom |
Subject: |
Re: [Discuss-gnuradio] Looking for more antenna details |
Date: |
Fri, 8 Sep 2006 13:40:34 -0700 |
User-agent: |
Mutt/1.5.9i |
On Fri, Sep 08, 2006 at 11:41:22AM -0600, Jim Borynec wrote:
> Hi
>
> I was looking at the picture:
> http://comsec.com/2x2-antenna.jpg
> and trying to replicate it (or something much like it).
Here's a closeup: http://comsec.com/2x2-antenna-closeup.jpg
> In the center of the ground plane, there appears to be a metal plate
> of some sort.
It's actually particle board covered with metal furnace tape. Turns
out that the adhesive on the tape is a pretty good insulator, so it
didn't work out that well. Just wrapping the board with aluminum foil
would probably work, or just use a piece of sheet metal. You want
something that's conductive and rigid and can be connected to the
hardware cloth. I used 1/4 inch square h/w cloth. I'd probably
go for the 1/2 inch square stuff next time. It's stiffer.
The PCV pipe is 1 inch schedule 40. You can stiffen the joints up by
slipping wooden dowels in place, then drilling a hole through the pipe
+ dowel for a bolt that will keep the dowel from drifting around.
> The anntenna appears to be attached to the plate via
> some sort of cylinder. what is that? does it contain a coil?
It's an SO-239 connector (Radio Shack). No coil or anything, it's
just there to serve as a socket for the antenna wire.
> What is the relationship of the plate to the antenna feed wire?
The plate's connected to the shield on the coax.
> how do you attach the ground plane to the cable without breaking the
> conection every time you more the assembly?
The cable is soldered to the back of the SO-239 connector. The shield
is effectively connected to the ground plane. There's no quick
disconnect, though you could build one. I just coil the coax up and
use zip ties to hold it to the screen while moving it.
Eric