Small Business Wireless Network - Antenna Advice

Question

I am trying to set-up a small network that will enable internet access into an external building about 90m away. However I would prefer access throughout the business area (being a farm, we would be able to access to the network from mobile devices then), which would be up to 150m but if this will be costly then there is no point. Meaning that the antenna should also be omni-directional.

There will be a total of 5 users maximum on this part of the network, so there should be no need for expensive equipment. There will also be little interference in terms of building work, as the antenna will be mounted outside to avoid the granite walls from our main building.

I have just ordered a new Netgear DGND3700 for our main router to handle requests, I am unsure if this will make any difference to what else I should buy?

So this leads me with the question, is there anything I should look for in the wireless access point and antenna? Or are there any antennas in-particular I should be looking to buy?

Please note this must be wireless, as if I were to wire the internet access it would be about 130m in cable and would work out far more expensive and we would still look to fit a wireless network in 2-3 years time.

Answer 1

You need to look at how long the cable run is going to be, between where you where thinking of mounting the AP and where you were thinking of mounting the antenna(s). Long cable runs are great at eating up 2.4GHz and 5GHz signals. It may be better to buy an outdoor-ruggedized, Power-over-Ethernet (PoE) capable AP, mount that on a pole on your roof, and run Ethernet to it. If you do buy antenna cable, only buy antenna cable that lists its 2.4GHz attenuation per meter.

You might want to actually calculate your "link budget" for both your outbuilding as well as separately for your mobile devices. There are online tools to help you do that, such as this:

http://huizen.deds.nl/~pa0hoo/helix_wifi/linkbudgetcalc/wlan_budgetcalc.html

Remember that you can put a high-gain directional antenna on the outbuilding, but you're right to put an omnidirectional antenna on your main building.

Beware that most online Wi-Fi range extension information pertains to single-radio designs from the a/b/g days. 802.11n is trickier because to get the highest rates, it uses more than one radio (the spec allows up to 4, but most gear just uses 2 or 3), so if you buy 802.11n gear and want to get 802.11n rates out of it, you need 2 or 3 separate antennas on each end, somehow set up so they don't interfere with each other too much.

Answer 2

You might want an inexpensive antenna booster http://www.freeantennas.com/projects/template2/

Basically your requirement for ADSL2+ limits your choices, especially in the long distance and custom firmware capable routers.

Answer 3

You need an access point which will accept an external antenna. Possibly one that uses power over ethernet if power is not available where you would like to mount the access point. That way you could mount the access point and antenna at the best possible location whilst minimizing antenna feeder losses. Start with a site survey and then work out what type of antenna will provide coverage bearing in mind eirp limits in UK.

Answer 4

My suggestion to you would be to put up smart antennas. Smart antennas are already in use in some locations. It can be used for directional broadcasting and frequency controls to achieve much more efficient use of radio spectrum, and therefore increasing the capacity of the system.