WiFi Cable Extension

[th3cl3ric]

Hi everyone,

Im trying to improve my wifi at home without buying a repeater or more gadgets, so I plan to use coaxial cables RP SMA Male - Female Extension to relocate my router antennas as in the picture bellow:

Is this possible? or it will be a loss in the signal and is not a good idea.

It will be great any advice

 

[Solandri]

It's hard to tell from your picture, but it looks like you're planning on 20-30 ft cable lengths? Unless you go with really thick cables, the signal loss at those distances usually offsets most of the gain from relocating the antenna. The problem is the thinner the cable, the greater the signal loss per ft. The higher the frequency, the greater the signal loss per ft. And 2.4 GHz and 5 GHz (really 5.2-5.9 GHz) are really high frequency. By comparison, cable TV/Internet is transmitted over coax at below 1 GHz, with a good chunk of it below 500 MHz.

https://www.wilsonamplifiers.com/blog/understanding-cable-length/
https://www.howtogeek.com/257784/how-much-wi-fi-signal-strength-is-lost-per-foot-of-antenna-cable-length/

Most people who want to relocate an antenna run an ethernet cable from a router/switch to an antenna location, and attach a WiFi access point there.

 

[truongcoi]

It is difficult to implement, need a more specific plan

 

[th3cl3ric]

It's hard to tell from your picture, but it looks like you're planning on 20-30 ft cable lengths? Unless you go with really thick cables, the signal loss at those distances usually offsets most of the gain from relocating the antenna. The problem is the thinner the cable, the greater the signal loss per ft. The higher the frequency, the greater the signal loss per ft. And 2.4 GHz and 5 GHz (really 5.2-5.9 GHz) are really high frequency. By comparison, cable TV/Internet is transmitted over coax at below 1 GHz, with a good chunk of it below 500 MHz.

https://www.wilsonamplifiers.com/blog/understanding-cable-length/
https://www.howtogeek.com/257784/how-much-wi-fi-signal-strength-is-lost-per-foot-of-antenna-cable-length/

Most people who want to relocate an antenna run an ethernet cable from a router/switch to an antenna location, and attach a WiFi access point there.

Hi, thanks for answer, actually my plan was to extend 15ft and 30ft with RG58 cable, but after read the link you provided, it seens I will have to buy a repeater :/

 

[vmfantom]

Oh yeah, it's possible. This is how RF engineers fronthaul outdoor antennas, and the main reason that cell towers can have baseband units at the bottom and sector antennas hundreds of feet up. And you should use http://www.timesmicrowave.com/calculator to figure out the attenuation for the cable product you pick.

I'm guessing your router puts out around 23 dBm per port since that's pretty typical. If you use the RG-6 you already have in your walls, 30 feet of RG-6 would have 4.8 dB of loss at 2.4 GHz. 23 dBm minus 4.8 dB is 18.2 dBm, so you'd have hardly lost any signal. You can split the signal as well. Let's say you want to split 8 times. 23/8-4.8 is -1.93 dBm. That's still stronger than your RSSI would be over the air just an inch or two from the router due to free space path loss.

You just need to convert the impedance if you aren't using 50 ohm end to end. L-Com has 50 ohm splitters and cable assemblies for industrial deployments and Coaxifi would have splitters and antennas for home deployments, or you can go to your local ham radio shop for heavier duty stuff. But your RSSI would stay above -60 dBm as far out as 500 feet.

The other answer mentions cable TV/Internet using coax below 1 GHz. Except that DOCSIS 3.1 goes up to 1.8 GHz and satellite LNB downconverters go up to 2.3 GHz. So the coax itself is clearly not a limiting factor. It just seems that people are hard pressed to find a good attenuation calculator online.

 

[th3cl3ric]

GREAT! thanks for the tip, I'll buy some RG-8 cables

 

[vmfantom]

GREAT! thanks for the tip, I'll buy some RG-8 cables

Just to make sure I'm not sending you down a rabbit hole:

RG-6 is what most people already have in their walls so you might not need to buy it. RG-8 (which you mentioned) is a different cable altogether and is 50 ohm rather than 75 ohm.

If you use 50 ohm cabling like RG-316, LMR-240, etc., then the setup would be: router antenna port <-- RP-SMA male connector on 50 ohm cable --- RP-SMA female connector on the same 50 ohm cable --> wifi antenna. 50 ohm is the native impedance for your wifi router.

If you use 75 ohm cabling like RG-6 (which is inexpensive and fine for short runs) to a standard coaxial wall plate then the setup would be: router antenna port <--RP-SMA to F female adapter <-- F male connector on 75 ohm cable -- F male connector on same 75 ohm cable --> F81 barrel connector on wall plate (F female on both ends) --> F male to RP-SMA female adapter --> wifi antenna. So it would go from 50 ohm to 75 ohm to 50 ohm.

Or you could use a home deployment kit from the company I mentioned earlier that has all those components integrated. That should work in your home so long as you have 'home run' cables running to each cable outlet rather than a daisy chain of cables.

(Full disclosure: I used to do installations for DirecTV and wireless ISPs, LMK if you have questions about setting things up)