long distance wi-fi

cOn Mon, 7 May 2007 17:10:45 -0500, wrote in :

Clear line of sight? If not, forget it. If so, forget about boosters and yagis, and check out dish antennas. See wikis below.

Hi, Visual LOS and radio LOS is two different thing. And even weather condition can affect signal path. Ever thought about reflector? If there is a WILL, there will be a way. My days of doing that sort of experimental thing is over.

Not really true. As it is dependent on many factors.

"Dana" hath wroth:

Really true but not for the obvious reason. NLOS (non-line of sight) is a problem not because you can't get a connection over the path. It's a problem becuase you can't maintain a connection over an obstructed path. Objects inside the Fresnel Zone cause all kinds of weird reflections, refractions, and blockages. Move anything a few cm in any direction and the path loss changes. Multipath just rips error rate because the reflected delayed signal arrives just when the next indicdent path packet arrives, causing them to clobber each other.

It is possible to do NLOS, but only if you have enough fade margin to compensate for the huge variations in propagation characteristics, and the perfect timing needed to deal with the multipath.

Even clear line of sight paths are not good enough for commercial microwave installations. Many have multiple radios and antennas for frequency diversity (to avoid frequency selective fadeing) and spacial diversity (to avoid atmospheric refraction). Of course, the longer the distance, the worse the problem.

In addition, there's the not so trivial problem of Fresnel Zone clearance. See:

Even a "block and a half" is a problem if the antennas are close to the ground (i.e. pointed through a window). My guess is that a "block and a half" is about 1000ft or 0.19 miles. That requires 8.1 ft radius clearance about the midpoint. That implies that the antennas on both ends have to be at least 8.1 ft off the ground, or the Fresnel Zone is going to hit the ground.

However, you're correct. It does depend on many factors, all of which conspire against NLOS being usable.

I'm curious how you rule out yagi antennas so quickly, especially since the length of the block hasn't been defined. My block is only

500ft long. I've done drive-bys with the biquad over that distance, though not at 11mbps.

On 8 May 2007 10:47:53 -0700, snipped-for-privacy@sushi.com wrote in :

Because they're a PITA. Easier to work with a dish antenna.

I am using a 4 foot long 15db omni and it picks up everything.