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keegster17
03-16-2012, 10:10 PM
I have a grid antenna on my roof, the roof is high up but I wold like to learn if I could connect to a pc or laptop for wifi. I think it is run into the house with a regular rg6 cable compression fitting is this possible? it is har to determine right now as the roof is high up and have not had a chance to follow the cable run. If I am correct did they ever use rg6 cable and fitting for wifi connection?

Tubbs
03-16-2012, 10:50 PM
hook it up, see what happends, you won't hurt it...

Terryl
03-16-2012, 11:07 PM
If it's using RG-6 coax then it wont work too good for WIFI, RG-6 will attenuate the signal from your WIFI device too much to be of any good.

You will also have to find some "F" to "Reverse SMA" adapters, (used on most WIFI devices with a removable antenna) those might be hard to come by.

The best way to to this would be to use an active WIFI device at the antenna, this will take a bit of work to setup, and that antenna may be one for TV signals.

Can you post a photo of it?

It will tell me a bunch.


Normal WIFI devices only put out about 50 to 200 mW of RF power, by the time it got to that antenna, the signal would be too weak and useless for any WIFI connection.

Terryl
03-16-2012, 11:08 PM
hook it up, see what happends, you won't hurt it...


Ahhh yes you could, sorry.

keegster17
03-17-2012, 04:55 PM
would I connect it to my modem? for what I can see the cable goes down in thru the house an i have one coaxial cable unconnected down by the electrical panel where all the local cable connections are for the whole house. I have a feeling this may be it, just unsure how and what to connect it too? I will post a pick when I get a chance. thanks guys, would love to test.

satchick
03-17-2012, 11:44 PM
It's probably a TV antenna, which would be totally useless for Wifi. The cable length would be a problem anyways, at 2.4ghz the signal drops off very quickly, usually with wireless installations you're limited to around 10ft of cable, and that's with the proper cable.

keegster17
03-30-2012, 12:15 PM
13928

guys here is a pic of the antenna. I am sure this is for Wifi?

japonc
03-30-2012, 12:31 PM
13928

guys here is a pic of the antenna. I am sure this is for Wifi?

get the alfa modem check if get any hotspot,(open free) get the router and you will be set to have wifi, easy as you read,
ps, need the cable to modem

Bigpineguy Retired
03-30-2012, 12:31 PM
13928

guys here is a pic of the antenna. I am sure this is for Wifi?

A better pic would help , but that looks like a 24DBI grid from what I could see....You would need to get up there to it, and write down any info that it says on it...you could then check the wire and see what you have, and where it leads....I use nothing less than LMN400 cable with N connector at grid, and reverse TNC Female into a linksys router flashed with dd-wrt acting as a repeater...if the wire is over 25 ' check into adding a 1 watt amp, and watch your internet bill disappear ...and it's a fun hobby as well

BPG~

Terryl
03-31-2012, 07:49 PM
And that antenna is also mounted up-side-down, the connectors should always come out the bottom side, keeps the water out.


And if that antenna is not designed for 2.5 GHz it wont work too good for WIFI, remember you also have to transmit the signal back to the access point, if the antenna is not resonate to 2.5 GHz, it will knock you TX return signal down so low you wont have a useful connection.

Receiving antennas don't have to worry too much about this, but when transmitting a signal, then you have to worry about the correct wavelength of antenna, and if the SWR* is too high, if the SWR is too high it could damage the transmit side of your router.

Most routers are transmitting at around 50 to 100 mW, the RG-6 coax will have 12 to 15 dB of signal attenuation at 2.5 GHz, it is also 75 ohms, 90% of transmit antennas are 50 ohms, this mismatch will also cause signal loss, and a high SWR on the transmitter.

Eventually this will cause damage to the transmitter.

Using an unknown antenna type for WiFi will cause more problems then good ones.

You can get good high gain yagi antennas for your WiFi, it would be better and safer on your router to do so.

Here is one that I have used.


http://www.radiolabs.com/products/antennas/2.4gig/14eleyagi.php

Avalanche
04-01-2012, 06:42 AM
Ive seen where some people put the DDWRT access point right out at the grid, inside an enclosure thats ventilated to reduce moisture.
Then they run back to the house with ethernet cable, and this apparently decreases signal loss.
This would technically be similar to an expensive P.O.E. (Power Over Ethernet) system.

IMO, I would rather have an omnidirectional antenna because it doesnt rely so much on line of site. Although grids are good for very long distance point to point connections. I think the record as of now is almost 100 km ?

Myself I use only a Linksys WRT54G (Rogers or Tmobile edition) with aluminum heatsinks installed for overclocking.
Attached to that I have only a D-link range booster antenna ( 7dbi) and I close it betweeen the window and the screen and I get wifi for many blocks away... (20 to 30 blocks away on a good day). Depending what youre using it for, pick the weakest signal as its usually the farthest away from home :D

There are some awesome guides out there to build an even larger scale Omnidirectional antenna using plain old pvc pipe and copper wire and they work great as an outdoor antenna.

Terryl
04-01-2012, 07:12 AM
I have one setup that goes 5 miles between two old "C" band dishes, the WIFI device is mounted where the "C" band LNB was.

Works great as the 7 foot dish happens to be resonant at 2.5 GHz, I made a holder for the 2 watt WIFI device, and a "T" adapter to hold the antenna, the device runs on a USB to CAT5 adapter, this runs into the house.

I got great signal with the old dish, worked wonders, we only had 3 signals before the setup, after we had 23, but the one we want is the strongest.

keegster17
04-01-2012, 01:25 PM
well tried to get closer, but no thanks, the roof is 30 ft. high, I had a near death experience, started to slide on old shingles. lol. really not funny. So case closed on this one for me. lol. I will need to find another option for a wifi antenna. I do have a couple ddwrt linksy routers, but I find the range not that great, no better than a usb network adapter, would this be a accurate statement?

Avalanche
04-01-2012, 05:58 PM
Definately not an accurate statement. You can adjust tx rates and other thinks in the DDWRT GUI that may help.
Positioning and interference from other devices and obstructions make a difference also.

You definately want an external antenna of some form connected to that to get the best out of it.
If you only have 1 antenna, make sure you set the transmit/recieve settings to use only 1 antenna, if your router has 2 antennas

satchick
04-01-2012, 06:19 PM
http://freemansgarage.com/blog/?p=157
There's an example of one way to set up an outdoor wifi antenna/access point for long range use. That's the route I would go if I were doing something like this; either a panel or a yagi antenna, with the router/AP in a weatherproof enclosure outside. Doing it that way keeps the antenna cable short, which is very important when dealing with high frequencies, as the signal attenuates very quickly when dealing with long cable runs.

Terryl
04-01-2012, 06:28 PM
well tried to get closer, but no thanks, the roof is 30 ft. high, I had a near death experience, started to slide on old shingles. lol. really not funny. So case closed on this one for me. lol. I will need to find another option for a wifi antenna. I do have a couple ddwrt linksy routers, but I find the range not that great, no better than a usb network adapter, would this be a accurate statement?


get one of these hummers.


http://www.nedsgadgets.com/p/Alfa-Awus036nh-2000mw-2w-802-11g-N-High-Gain-Usb-Wireless-G-N-5072426.html

Then some USB to CAT5 adapters, you can put the 2 watt* TX/RX unit inside a 3" piece of PVC pipe to keep it out of the weather.

2 watts = 2000 mW, normal WIFI routers have 50 to 100 mW (.05 to .1 watt), so you can see the big gain in signal.

This is as strong a WIFI adapter you can get without breaking your wallet.

It also has a removable antenna, so you can add a good sized yagi to it, this setup is the heart of my 5 mile WIFI hop.