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If you connect an access point to (PCIe/USB) Wifi card over coax (i.e. no antennas) will it work?

If it would work, what would the maximum cable length be?

(This is just a thought experiment. I know fiber optic cable is better for long distance networking.)

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  • \$\begingroup\$ I don't know if it would work. The range depends on your cable. The WLAN input sensitivity is probably in the range of -70dBm. The output level is in the range of 15-20dBm. So you have ~85dB for cable loss. \$\endgroup\$ Mar 19, 2014 at 10:22
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    \$\begingroup\$ Feeding 15-20dBm directly into the antenna is probably not great for the receiver. I'd say 30-40dB of attenuation would be advisable. \$\endgroup\$
    – markt
    Mar 19, 2014 at 10:33
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    \$\begingroup\$ If you're running a cable anyway, why wouldn't you just use regular wired Ethernet? CAT6 is a lot cheaper than coax. \$\endgroup\$
    – Dave Tweed
    Mar 19, 2014 at 13:15
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    \$\begingroup\$ OP is not looking for practical solution to a particular problem, though. It is a curiosity/thought experiment question. \$\endgroup\$
    – dext0rb
    Mar 19, 2014 at 16:29
  • \$\begingroup\$ And I always thought the WiFi cable is a joke! \$\endgroup\$ Sep 1, 2016 at 13:43

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If you used RG-58 at about 1dB loss per meter, you could theoretically run a cable of about 80 to 100 meters, depending on the output power of your transmitter. In reality, I would rather keep it to 50-60 meters and place a 5 dB attenuator at each end to make sure I wasn't saturating the receiver. You can take out the hard attenuation when you're done but I like to gradually work up to full power to make sure there aren't any kinks.

Also, if you want to hook up multiple devices, just have your clients linked through a power divider (2-way, 4-way, etc.).

Basically (excuse my first time math syntax)

\begin{aligned} \ distance = \ (PowerOut - ReceiverMinimum)/ dBLossPerMeter \\ \ \ \end{aligned}

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    \$\begingroup\$ This is a shorter distance than I expected. I thought that people had made Wifi go kilometers with Pringle can antennas - why isn't a coax cable better than air? \$\endgroup\$
    – Mark Smith
    Mar 19, 2014 at 15:51
  • \$\begingroup\$ That's because A) it depends on transmitted power and B) I chose RG-58 arbitrarily. LMR-1700 is 0.056 dB/meter and is probably pretty expensive and you could get a few kilometers out of it. Keep in mind, this is passive without any additional amplification. You could add and amplifier halfway and boost your signal. Regardless, this is one of the many reasons that coax lines aren't run for miles and miles at a time. Data is digitized, amplified, converted to different data types, etc. \$\endgroup\$
    – scld
    Mar 19, 2014 at 16:04

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