I wonder what level of humidity that 2 dB per kilometer figure is for? Is that typical or worst case?
At 20 kilometers (about 12.4 miles), a distance this ISP is trying to serve some customers at, that 2 db becomes 40db.
Overcoming an additional 40 db loss would require increasing the power by a factor of 10,000 times. They're using amplifiers and directional antennas but the fade margin is nowhere near 40 db. And they do have fading problems. Of course refraction/reflection from temperature/humidity inversion gradients and other propagation effects come into play too. It isn't just simple absorption.
Are we still talking about WiFi? The one with coverage limited in fractions of a kilometer? Achieving 20 km coverage radius (or even targeted coverage) sounds like a sisyphean task to me.
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I wonder what level of humidity that 2 dB per kilometer figure is for? Is that typical or worst case?
At 20 kilometers (about 12.4 miles), a distance this ISP is trying to serve some customers at, that 2 db becomes 40db. Overcoming an additional 40 db loss would require increasing the power by a factor of 10,000 times. They're using amplifiers and directional antennas but the fade margin is nowhere near 40 db. And they do have fading problems. Of course refraction/reflection from temperature/humidity inversion gradients and other propagation effects come into play too. It isn't just simple absorption.
Are we still talking about WiFi? The one with coverage limited in fractions of a kilometer? Achieving 20 km coverage radius (or even targeted coverage) sounds like a sisyphean task to me.
I dont know how they do it but the longest range wifi link is 382km[1]. And 10 km with good directional antennas is not that special, really.
[1] http://www.slideshare.net/1ereposition/long-distance-wifi-tr...
Wow, that's actually kind of exciting (and disturbing!), even though the link is unstable. Thanks for the info.