Connecting two houses 0.44mi apart Setup Question

Connecting two houses 0.44mi apart Setup Question

Postby L8Nighter » Sat Jan 18, 2003 10:48 pm

Any help on setting this up right would be grateful.

Ok using a GPS I have calcuated that the houses are 0.44miles apart and 30 deg from true North from one of the houses to the other. Using the calcuations on the web it states at 2.4GHZ and 0.44mi there is 9 ft from dead center of each antenna.

Problem is there is maybe 3-4 houses in direct sight between each house and im wondering which antenna design would be the most effective? I am wanting to also use 802.11G and wondering if I can get 45mb with the houses in the way and at this distance?

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Connecting 2 nodes 1/2 mile apart...

Postby skeez » Sun Jan 19, 2003 9:36 am

For 802.11b (2.4GHz) you need a CLEAR line of sight for a stable network bridge. You stated you have several houses in direct line of sight between your two nodes, this does not sound encouraging. While it is possible to transmit through some obstacles, there are a number of things that can affect your signal. In fact there are too many variables to calculate and really would not be worth your time to do so. Just for consideration, the 2.4GHz signal will be completely blocked by a sheet of metal, and then it can actually be filtered or deflected by a material that the signal would have penetrated if struck at a 90 degree angle.

I would recommend you look into mounting your antennas on masts high enough to clear the other houses. If this is possible, the following calculations should get you at least an idea.

Distance between nodes: 0.44 mile = 2323.2 ft or 0.70811136 km

Your antenna height (H) can be calculated using the following formula:

H = Z+C+H

Value of the Fresnel zone: 6 (Z) - 60% for 802.11b's frequency
Curvature of the earth: .75 (C) - Plays a minor role at this distance
Obstruction height: 25 ft (H) - Average height of single story home

Result: 31.75 ft

The Fresnel zone takes into consideration objects and obstructions and their effect on radio waves. At 2.4GHz, for 1 mile use a value of 10, 5 miles: 30, and 10 miles: a value of 45.

To make a long story short, if you were to use a decent quality (5dBi gain) Yagi or another directional antenna at both sites, and got them 4 or 5 feet above the highest obstacle, then drive them both with a decent access point or bridge (30mW) you should be able to get decent 5.5mb (+/-) connection.
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Postby Fritzo » Tue Feb 04, 2003 11:40 am

Or, so you can do like I did and mount the antenna on an 8FT pole on my roof, then had my buddy do the same. We used FRS radios to make aiming adjustments and it worked great. We were about 1500 ft. from each other, so not quite your ".44 miles" away. Project took about 2 hours. Now we have a nice wireless gaming LAN and don't have to leave our cozy houses :)
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