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This is just extending the antennas using 50-ohm cables. By using couplers and multiple cables, you can connect multiple antennas to the same access point. It
by EarthIsHome 6y ago
This is just extending the antennas using 50-ohm cables.
By using couplers and multiple cables, you can connect multiple antennas to the same access point.
It's a way to physically separate the antennas from the router by using a coax cable.
- q3k 6y agoHome TV coax has a characteristic impedance of 75ohm. If you just plug consumer devices in directly you will get a pretty significant SNR loss from reflections and other impedance mismatch effects.
- EarthIsHome 6y agoSure. But I would bet that most Wi-Fi access points use a 50-ohm system. (Plus, the connectors on a home tv coax cable probably won't mate with the router connectors.) If you want to use a 75-ohm cable, you'll have to use impedance converters to convert to 50 ohms. Bottom line: just make sure the components you're connecting in your system are properly matched to avoid a lot of reflections and power loss.
- kazinator 6y ago> If you want to use a 75-ohm cable, you'll have to use impedance converters to convert to 50 ohms. ... says the article, clearly.
- dboreham 6y agoThis confused me but I think you mean "Most WiFi Access Points use a..."?
- EarthIsHome 6y agoThanks! Corrected
- kps 6y agoDoesn't everyone have a stash of old 10base2 cables? The idea of running a network over them is strangely appealing.
- segfaultbuserr 6y agoImpedance matching is overrated, the return loss of 50-ohm into 75-ohm is 14 dB, or a VSWR of 1.5:1, it means a low reflection, in practice the return loss is even better due to the loss in the cable. Also, unlike some digital systems that are expected to operate in a controlled environment, Wi-Fi is designed to work with multipath interference, so running Wi-Fi over 75-ohm coax can already get better SNR than running it over-the-air, so matching is not always necessary. You can always add one at the last step if it turned out to be necessary.
- superkuh 6y agoThe mismatch loss between 50 and 75 ohm cable is 0.4 dB (or ~5%). It's not really significant unless you're doing small signal work (which wifi isn't) or if you're doing high powered work where 5% loss heats the coax (which wifi isn't).
- himinlomax 6y agoWouldn't there be a problem with reflection? Attenuation is not the issue here, reflecting even a fraction of a strong enough signal could potentially even be destructive for the device. It's possible though that WiFi devices, particularly those with coax ports, have protection against this.
- superkuh 6y agoStanding wave ratio would be 1.5. Peak powers under 1 watt (and probably under 600mW). The transmitter is going to be fine.
- baybal2 6y agohttps://www.soontai.com/IMPEDANCE-CONVERTER.html https://www.soontai.com/IMPEDANCE-CONVERTER.html
- kazinator 6y agoWhy extend the antennas? They are hooked up to your router with a coax connector. You're already doing Wi-Fi over coax!