Re: Dipole v. Omni
- From: dold@xxxxxxxxxxxxxxxxxxxxxxxx
- Date: Sat, 2 Jul 2005 05:35:49 +0000 (UTC)
DanR <dhr22@xxxxxxxxxxxxxx> wrote:
> my head but I pick up some of it. Could you explain what "broadside to
> each other" means and what is meant by "opposite each other".
My "broadside": Don't point the antennas at each other like a flashlight.
That's not the way the radiation goes. Think of a CDROM with the antenna
half way up through the hole in the CDROM. The CDROM represents a
flattened version of the radiation coming from the dipole antenna.
Point the edges of these imaginary discs toward each other, from the WAP
and the client radio.
That's my view of the world, from a background with 200MHz 5Megawatt
What Floyd is saying is that WiFi bounces around quite a bit, and if it
isn't clean air between transmitter and receiver, it's hard to say what the
best antenna orientation is. In my house, it's not a direct line. Moving
a foot or two in the living room changes the best vertical/horizontal angle
as well as the direction of the antenna. In one spot, I'm better off
pointing toward a window that is not in a direct line with the WAP, but is
apparently still letting in more signal than the wall. A couple of feet
away, I am better pointing toward a hallway, which is quite a bit off from
line-of-sight, but has no obstructions, just a hallway to bounce the signal
around. Orientation from vertical to horizontal is also worth a couple of
points on the NetStumbler display.
If you are running to a fixed point, then you could just move things around
until you find the best orientation. I used my desktop computer and
laptop, running VNC or Microsoft RDC to view the other screen. One at the
WAP, one in the living room. I would view a signal meter at the opposite
end, and move things around. If your WAP has two antennas, they might want
to be at 90 degree angles to each other. Or not.
> I have the typical Linksys wireless router and always wonder what the
> best theoretical antenna position is. Both straight up (parallel) or both
> straight back (parallel) or both at 45 degrees spreading left / right of
> the router or
I have a Linksys BEFW11S4 upstairs. I have both antennas parallel to the
floor, and angled so the edge of the imaginary disk is pointed in the
general direction of the PCs downstairs. The two antennas are parallel to
each other. They also each have a www.Freeantennas.com EZ-10 reflector.
Here are those two reflectors in a previous location:
Jeff thinks my aluminum foil is too wrinkly. I think that's an optical
Here's the replacement WAP in that same spot, with a single antenna so
there are no difficult decisions to make, and the nicer-looking
www.Freeantennas.com EZ-12 Windsurfer reflector.
http://www.rahul.net/dold/clarence/EZ12-windsurfer.jpg The aluminum foil is
very, very smooth, on the back side of the upright "sail". (Trust me,
Jeff.) There should be less signal going out the back wall of the house
than there was with the bare antenna, and more into the house, and out the
other side, toward the deck. Some predictions of the signal pattern are on
the Freeantennas site. The effect for me is here:
http://www.rahul.net/dold/clarence/windsurfer-dining.JPG The signal with
the reflector is not only 13dB stronger, it's more stable.
Clarence A Dold - Hidden Valley (Lake County) CA USA 38.8,-122.5
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