Big Fun With The Technical Stuff—continued

Engaging signal killers
In another location I have access to a short tower on a hill. The tower is about 100-yards away from a huge, solid metal water tank that is about twice as all as my hilltop tower. I hope to get on the water tank some day, but for now I've established connections that work just fine from the short tower.

I used sectored antennas and left a "gap" in coverage where the water tank is located to help eliminate reflections from its metal surface. I've got one customer 11-miles (18 Km) away from the link, and the customer says that he gets about 60K/sec FTP transfers over the second hop of the 2meg distribution system.

I also built a "shade" for my omni antenna here in Odessa, Washington. There is a cell phone PTP link that is within a half-mile of my location—they really hit my system hard with a lot of interference in the 2.4GHz range, killing everything below channel 8. I sit on channel 11, but I still needed to cut down interference from their signal. So I put a piece of pipe between their antenna and mine. It dropped the noise level down by a noticeable, but not measurable amount. Customers picked up a few K/sec of speed, even though we should have been fine with our channel selection—go figure.

For customers that are really close to my base station—two miles or less, I've had pretty good luck with connecting them by putting up an 18dB patch antenna right inside their home. There are types of home construction that work-well with this method of linking signals, and others that it don't work at all. Expect trial-and-error installations to be your guide.

Can do, usually does
Don't be afraid to try things that so-called "experts" tell you can't be done. It's all just a numbers game. Different materials possess different properties and as long as you don't give a link too little or too much power, you can do some really fun things when you understand the basics.

Remember, always keep safety at the top of your list of priorities. Network reliability should be your second goal, which allows price to factor into the equation as your third consideration. I guarantee you'll have a lot of fun learning what works for your fixed wireless system—each of which is a unique proposition because they are all different in one way or another.

I don't have many trees here, but most homes are surrounded by them. It doesn't do much good to build a great signal that lands to a point within 50-feet or so of where you need it! For lots of trees I've had better luck setting up a 45-degree angle on my antennas than by using horizontal or vertical polarized antennas—and I've never seen a 45-degree angle on an omni antenna (wink, wink).

Instead of greenery, you may have a lot of water to contend with in your fixed wireless service area. Some people seem to like vertical polarization patterns for linking antennas over water, while others have made horizontal polarization work for their system. I say, try one of each and see what works best with rest of the terrain that is your immediate service footprint.

I hope some of the elements of antenna setups discussed here today will be of help to you. Your choice of antennas will make or break your wireless system, just like the choice of speakers will make or break a stereo system. Use the good stuff and even an inexpensive system will astound your customers!

— End

Part 1: How to Pick the Perfect Antenna	Part 2: Big Fun With The Technical Stuff
< Go to page 2	Go to page 2 >

Related articles:
	[Apr. 17, 2001]	Part 1: How to Pick the Perfect Antenna
	[Feb. 5, 2001]	Wireless LAN Primer
	[Dec. 15, 2000]	FW: A Method For Broadband Internet Access

If you have a story about an antenna installation that went awry or an interesting way that you overcame interference while setting up a fixed wireless system, send it to the editors@isp-planet.com. Share your experience as a lesson to help guide other fixed wireless service providers through your installation innovations.