Reaching A Distant Wireless Access Point (wifi antenna)

weirdjim · 10-02-2004

My current dialup ISP has placed a wifi antenna (WAP) on top of a tree some quarter of a mile away. This is a rather mountainous rural area with a lot of tall pine trees between this antenna and the top of my house, although with a regular laptop computer and the wireless card in the lappy, we can JUST BARELY get a signal if I stand on top of the house.

This is difficult to do in the winter, and uncomfortable as hell in snow and blazing sun.

We currently have two desktop computers linked wirelessly through a Netgear router/switch with one of us hardwired and the other one wireless.

What I'd like to do is use a gain antenna to simply RECEIVE this weak signal from my ISP and retransmit it into our current wireless environment.

I have a Linksys wireless-G broadband router with dual rubber-duckie antennas, and the thought is to use a gain antenna on ONE of the antenna ports and let the other rubber duck antenna reradiate the signal into both of our machines.

Somehow it doesn't seem to work that way. My bag is microwave antennas, not digital gimcrackery. Any suggestions as to what to read, where to ask, and all that stuff would be most appreciated.

No, we aren't planning to steal access from my ISP. We plan to pay for the service just like anybody else, but he is not capable of any help in the router/antenna/switch interface.

Jim

Thorn · 10-03-2004

Quote:

Originally Posted by weirdjim

...
We currently have two desktop computers linked wirelessly through a Netgear router/switch with one of us hardwired and the other one wireless.

What I'd like to do is use a gain antenna to simply RECEIVE this weak signal from my ISP and retransmit it into our current wireless environment.

I have a Linksys wireless-G broadband router with dual rubber-duckie antennas, and the thought is to use a gain antenna on ONE of the antenna ports and let the other rubber duck antenna reradiate the signal into both of our machines.

Somehow it doesn't seem to work that way. My bag is microwave antennas, not digital gimcrackery. Any suggestions as to what to read, where to ask, and all that stuff would be most appreciated.
...

First, adding an higher gain antenna to one antenna port of the Linksys router will not work. This is due to "antenna diversity." Only one antenna is used at a time. Internal circuitry switches to the antenna with the better signal. This avoids multipath issues. If you have an understanding of microwaves then multipath should be at least somewhat familiar to you.

You will need either another AP, or a wireless bridge to talk to the ISP's AP.

Secondy, you will essentially need to have TWO networks, one on the ISP's side, and one on your home's side. Althought it is all "digital gimcrackery", you should start reading up on Networking 101

weirdjim · 10-03-2004

First, adding an higher gain antenna to one antenna port of the Linksys router will not work. This is due to "antenna diversity." Only one antenna is used at a time. Internal circuitry switches to the antenna with the better signal. This avoids multipath issues. If you have an understanding of microwaves then multipath should be at least somewhat familiar to you.

That makes the problem several orders of magnitude larger. No, I did NOT know the two antennas were there for diversity. I was sort of hoping that they were going to a summing junction of some sort, but that evidently is not the case. Sigh.

That sort of prevents another scheme, reradiation, unless I do it passively, and that doesn't seem too practical given the low level of signal that is there. Passive reradiation simply means picking it up with one antenna aimed at the distant access and feeding it into another antenna that is aimed at the shop's router. I suppose it MIGHT work if I could assure that the router will stay in one place in the shop, or that I would reaim the internal antenna if it got moved.

I'm going to port this discussion over to ANTENNAS part of the forum. Thanks for explaining it to me.

Jim

Thorn · 10-03-2004

A passive setup may work. Some people have reported amazing results using things like two 24dBi dishes and a 1ft section of LMR-400. Others have attempted similar setups and have reported that the losses are too much to do anything useful. Obviously, it will depend a great deal on the signal level you're seeing at the roof.

One variation that you might consider it a reflector panel.

The Antenna Forum is one of the FAQ forums, and is therefore read only. The Hardware Forum is the place that antenna discussions usually take place.

Safecrackr · 10-06-2004

With 3rd party firmware you can turn off diversity spread giving you the option to choose which antenna to be used for tx/rx.

10-02-2004	#1 (permalink)
weirdjim Registered Member Join Date: Oct 2004 Posts: 5	Reaching A Distant Wireless Access Point (wifi antenna) My current dialup ISP has placed a wifi antenna (WAP) on top of a tree some quarter of a mile away. This is a rather mountainous rural area with a lot of tall pine trees between this antenna and the top of my house, although with a regular laptop computer and the wireless card in the lappy, we can JUST BARELY get a signal if I stand on top of the house. This is difficult to do in the winter, and uncomfortable as hell in snow and blazing sun. We currently have two desktop computers linked wirelessly through a Netgear router/switch with one of us hardwired and the other one wireless. What I'd like to do is use a gain antenna to simply RECEIVE this weak signal from my ISP and retransmit it into our current wireless environment. I have a Linksys wireless-G broadband router with dual rubber-duckie antennas, and the thought is to use a gain antenna on ONE of the antenna ports and let the other rubber duck antenna reradiate the signal into both of our machines. Somehow it doesn't seem to work that way. My bag is microwave antennas, not digital gimcrackery. Any suggestions as to what to read, where to ask, and all that stuff would be most appreciated. No, we aren't planning to steal access from my ISP. We plan to pay for the service just like anybody else, but he is not capable of any help in the router/antenna/switch interface. Jim

10-03-2004	#4 (permalink)
Thorn Did you do the math? Join Date: Apr 2002 Location: Villa Straylight Posts: 10,083	A passive setup may work. Some people have reported amazing results using things like two 24dBi dishes and a 1ft section of LMR-400. Others have attempted similar setups and have reported that the losses are too much to do anything useful. Obviously, it will depend a great deal on the signal level you're seeing at the roof. One variation that you might consider it a reflector panel. The Antenna Forum is one of the FAQ forums, and is therefore read only. The Hardware Forum is the place that antenna discussions usually take place. __________________ Thorn "I'm The Doctor. I'm a Time Lord. I am from the planet Gallifrey in the constellation Kasterborous. I'm 903 years old and I am the man who is going to save your lives and all 6 billion people on the planet below... You got a problem with that?"

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10-03-2004	#3 (permalink)
weirdjim Registered Member Join Date: Oct 2004 Posts: 5	First, adding an higher gain antenna to one antenna port of the Linksys router will not work. This is due to "antenna diversity." Only one antenna is used at a time. Internal circuitry switches to the antenna with the better signal. This avoids multipath issues. If you have an understanding of microwaves then multipath should be at least somewhat familiar to you. That makes the problem several orders of magnitude larger. No, I did NOT know the two antennas were there for diversity. I was sort of hoping that they were going to a summing junction of some sort, but that evidently is not the case. Sigh. That sort of prevents another scheme, reradiation, unless I do it passively, and that doesn't seem too practical given the low level of signal that is there. Passive reradiation simply means picking it up with one antenna aimed at the distant access and feeding it into another antenna that is aimed at the shop's router. I suppose it MIGHT work if I could assure that the router will stay in one place in the shop, or that I would reaim the internal antenna if it got moved. I'm going to port this discussion over to ANTENNAS part of the forum. Thanks for explaining it to me. Jim

10-06-2004	#5 (permalink)
Safecrackr Registered Member Join Date: Oct 2004 Posts: 6	With 3rd party firmware you can turn off diversity spread giving you the option to choose which antenna to be used for tx/rx.