Wireless Antenna between two buildings (small business)

[n0fx]

I have two buildings, in which I need to connect to each other. I've been trying to figure out what would be the best method to approach this. The two buildings are around 1.45miles from each other (taken from the longitude/latitude) on google, straight pathway. I was wondering if you guys can provide some input on how I would go about this.

1. The main location is really close to a small airport (maybe 1/2 mile south). The second location is northwest from the main building, so it's the opposite direction of the airport)
2. I'm trying to connect both buildings via wireless with at least 10 to 20 mbit in bandwidth. I was thinking of the Engenius EOR7550 as a possibility.
3. How can I determine if LOS or nLOS would be possible? Can I do the site survey myself and should I get a professional do come by to look at it and evaluate it? I don't think I can see the other building from the roof at the main location.
4. If LOS/nLOS is there, would I need any permits and such if I erect an antenna for a setup like this using the standard 2.4GHz or 5.8GHz bands, if I really need to get the antenna high up to be able to connect to each other?

 

[overdrive31]

For direct LOS which most all 2.4 and 5GHz radios require you may need to put them up high. A 900MHz radio doesn't require so much of a direct LOS. Those radios should do well with external directional antennas, at that distance probably only the 2.4GHz would make it. However, I have read that the 5GHz radio designed to provide backhaul can reach up to 5 miles with good external directional antennas.

 

[n0fx]

For direct LOS which most all 2.4 and 5GHz radios require you may need to put them up high. A 900MHz radio doesn't require so much of a direct LOS. Those radios should do well with external directional antennas, at that distance probably only the 2.4GHz would make it. However, I have read that the 5GHz radio designed to provide backhaul can reach up to 5 miles with good external directional antennas.

Thanks for the suggestion. Do you have any recommendations in terms of which would be good for 900MHz antennas?

 

[overdrive31]

Few drawbacks with using 900MHz, is low bandwidth from 1-4mbps, short range(1-2 miles), and equipment may not be as economical. You might try using some Link calculators to determine possible LOS. I would seek a local WISP for tips on equipment and licensing.

 

[stevech]

I have two buildings, in which I need to connect to each other. I've been trying to figure out what would be the best method to approach this. The two buildings are around 1.45miles from each other (taken from the longitude/latitude) on google, straight pathway. I was wondering if you guys can provide some input on how I would go about this.

suggestion

Redline AN80i, 2ea

less desirable for 1.5 mi path (line of sight)
Engenious bridge pair, 802.11a. See newegg.com

 

[n0fx]

suggestion

Redline AN80i, 2ea

less desirable for 1.5 mi path (line of sight)
Engenious bridge pair, 802.11a. See newegg.com

Thanks, I'll definitely look at the redline AN80i!

 

[keenanj]

line of sight means no buildings, earth or other structures between the two points. However light tree cover is ok at 1/2 mile distance.

All you need is a pair of the engenius eoc2611p outdoor bridges

http://www.keenansystems.com/store/catalog/product_info.php?cPath=2&products_id=315

They will work better for your application the the eor7550

 

[n0fx]

line of sight means no buildings, earth or other structures between the two points. However light tree cover is ok at 1/2 mile distance.

All you need is a pair of the engenius eoc2611p outdoor bridges

http://www.keenansystems.com/store/catalog/product_info.php?cPath=2&products_id=315

They will work better for your application the the eor7550

How will it work if the distance is 1.5 miles, it's more than 1/2 a mile and what type of bandwidth will I get in a real world scenario with the Engenius setup?

 

[keenanj]

I ran a quick calculation with the WiFi range Calculator app

http://www.keenansystems.com/store/WiFi_range_calculator_for_iphone_and_ipad.htm

With a scatter exponent of 3 range between 2 eoc2611p units is 1.9 miles.

 

[stevech]

Also... lots of link budget (path loss) calculators on the web, such as
http://www.webcooltools.com/Engg/m&rf/FSPL2.html

which works for free space line of sight, no obstructions.
Set units to feet or meters.

Some indoor figures for obstructions...
take free space path loss and add the loss for drywall, about 2db per layer (4dB per wall) at 2.4GHz (per NIST report on construction materials). Masonry is higher.

Terrain is essentially a no-go at 2.4GHz. As is significant foliage.

in addition to the web site, enclosed is an excel sheet.

it includes the Fresnel loss calculation - mostly for point to point links of a mile or more.

In WiFi, the received signal strength determines what bit rate can be achieved among the rate options in 11g vs. 11n. Stronger signal, the hardware shifts to a higher speed. Your "net" speed depends too on how much competition there is for air-time, amongst nearby systems.

In the spreadsheet, the transmitter power to use
laptop, 11g/n mode: 30mW (0.03 watt), due to the "OFDM backoff" issue.
laptop, 11b mode: 100mW
WiFi router- often the same radio as in laptops. Some products provide a bit more, say, 60mW in 11g/n.

30mW vs. 100mW is a small number of dB. So in the path loss link budget, compared to the path loss, a few dB is not very significant. Which is why high gain antennas (like 10dB or more) make all the difference.

 

[n0fx]

Also... lots of link budget (path loss) calculators on the web, such as
http://www.webcooltools.com/Engg/m&rf/FSPL2.html

which works for free space line of sight, no obstructions.
Set units to feet or meters.

Some indoor figures for obstructions...
take free space path loss and add the loss for drywall, about 2db per layer (4dB per wall) at 2.4GHz (per NIST report on construction materials). Masonry is higher.

Terrain is essentially a no-go at 2.4GHz. As is significant foliage.

in addition to the web site, enclosed is an excel sheet.

it includes the Fresnel loss calculation - mostly for point to point links of a mile or more.

In WiFi, the received signal strength determines what bit rate can be achieved among the rate options in 11g vs. 11n. Stronger signal, the hardware shifts to a higher speed. Your "net" speed depends too on how much competition there is for air-time, amongst nearby systems.

In the spreadsheet, the transmitter power to use
laptop, 11g/n mode: 30mW (0.03 watt), due to the "OFDM backoff" issue.
laptop, 11b mode: 100mW
WiFi router- often the same radio as in laptops. Some products provide a bit more, say, 60mW in 11g/n.

30mW vs. 100mW is a small number of dB. So in the path loss link budget, compared to the path loss, a few dB is not very significant. Which is why high gain antennas (like 10dB or more) make all the difference.

Thanks so much for the info. I'm going to run some calculations and see what I can come up with.