Comment by obi1kenobi
2 years ago
I'm the author. Among other things, it's a distance problem -- WiFi can go through walls when the router is right there. But distance attenuates the signal as distance squared, and in this case we're talking about hundred+ yards/meters instead of just a couple.
> in this case we're talking about hundred+ yards/meters instead of just a couple.
Sure but didn't you say you were using directional antennas?
No antenna is directional enough to overcome n^2 scaling. Especially not the mid-tier consumer-grade hardware I would have had access to at the time.
Rough rule of thumb, a consumer-grade directional antenna (at least at the time, maybe they've improved in the last 10yrs) will give your signal strength a one-digit multiplier (say ~8x), meaning ~7-10dB. But that n^2 means that improvement only takes you 2-3x farther, not 8x.
Here we're talking about ~100x the distance, which would need a 10000x = 40dB improvement in signal strength. AFAIK an antenna like that would cost more than the entire city block where I grew up
Won't 20dB at each end do the job? You can get 16-17dB antennas for $35 these days. And a wire parabolic dish promising 23dB for $200.
7-10dB matches the antennas I personally use, but those antennas are smaller than my phone. You can get a lot more out of a three foot spike or a two foot dish.
(I'm assuming 2.4GHz and hoping they're not lying about the gain.)
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Free space path loss over 5 meters with non-directional antennas is the same as over 500 meters with 20 dB of gain at each end.
a directional antenna increases the gain of the signal, but it doesn't fix the problem of decreasing with square of the difference and physical objects blocking signal. If the distance was already near the maximum, it wouldn't take much to block it.
Fair point. I suppose it's very much device dependant. The P2P stuff I've used was good for a few km.