Farm Industry News


WHEN ROD KELLER wanted to network his home office computer to a laptop in the shop several years ago, he used his skills as a computer hobbyist to build a wireless technology system.

After experimenting with various extended-range antennas, he was able to expand the reach of his wireless network from the advertised 300 feet to two miles or more. So connecting his home and main farm sites near Clarion, IA, which are about a mile apart, was relatively simple.

When Keller began his wireless connectivity quest, he studied the basics of microwave radio technology and began experimenting. Since then, Keller, who farms 1,300 acres with his brother Dave and mother Ev, has opened a Radio Shack franchise in his hometown to capitalize on his growing technology expertise.

According to Keller, setting up a home-to-shop wireless network is within the capabilities of the technologically savvy. “Working with somebody who has done this before also is helpful,” he says.

Brian Getzschman, who runs Omni-Tech, a computer, networking and data services company in Fremont, NE, concurs with Keller's assessment. “The skills get more specialized when you want to go long distances, but a short hop is within the capabilities of competent do-it-yourselfers,” he says.

If you are one of those do-it-yourselfers, or just want to get a handle on how this technology works, here are the basics.

Wireless 101

The wireless technology discussed here uses high-frequency radio waves, or microwaves, most often in the 2.4- or 5.8-gigahertz (GHz) frequencies. These frequencies inhabit the wavelength range just longer than visible light and shorter than frequencies used in cellular telephones and commercial radio and television broadcasting. The 2.4-GHz spectrum, which is used most frequently, is the same one used by microwave ovens and many cordless telephones. Frequencies in this spectrum are available for general use without a license if transmission power is below 1W, which is typical. Radio transmission at these frequencies requires that antennas have a direct line of sight.

“Line of sight and height of antennas off the ground mean the world with this technology,” Keller says. Though microwave signals pass through buildings and other obstructions, the signal strength degrades. Growing plants are especially problematic, because the moisture in leaves is excited by the microwave just as it would be in a microwave oven. Wattage is much lower (a fraction of a watt versus 1,000W in many microwave ovens), so the effect on the plant isn't noticeable. But the impact on the signal can be significant.

“If this little 100-milliwatt signal hits a tree leaf, it sucks the signal out of the air; the same with corn,” Keller says.

Build a network

Assuming that a direct line of sight installation is possible, building a wireless system between a house and a nearby shop requires a short, relatively inexpensive list of equipment, including two wireless access points (WAPs), two antennas and associated mounting masts, and specialized cable to connect the access points to the antennas. It should cost $500 or less, unless you hire outside expertise or labor.

Typically, this system will use 2.4-GHz WAPs using the 802.11b communications standard. These devices, manufactured by D-Link, LinkSys, Engenius and others, convert a computer's digital signals to radio waves. These WAPs normally are used for in-house wireless networks and are available at most computer stores. Although WAP devices with the “a” and “g” variants of this standard are available, Keller and Getzschman say that the “b” standard is preferred in this setup because of superior reach and less potential for interference. Be sure to buy WAPs that have an external antenna hookup. Expect to pay $50 to $100 for each WAP.

The preferred antenna for this installation is a parabolic grid antenna supporting 2.4-GHz radio communications. Antennas are rated for the amount of gain they provide. You will want antennas with at least a 12-decibel (dB) gain for an installation covering 500 yds. An antenna with a 19-dB gain should work for distances of a mile or two. Some computer stores sell these antennas, but online sources may be more plentiful. An Internet search for “parabolic grid antenna” will turn up multiple options. Expect to pay $40 to $80 for each antenna.

You'll need LMR400 cable with dedicated couplers to connect the WAPs to the antennas. This low-loss coaxial cable may be hard to find at a computer store but should be available from most companies selling parabolic grid antennas. Expect to pay at least $25 for a 20-ft. cable with connectors. You'll need one cable for each location.

Be sure to install the WAPs inside a structure, because they probably won't be weatherproof. You will need Ethernet cable to connect the WAPs to your computer or router.

Once the installation is complete, antennas must be pointed at one another and WAPs will need to be configured to set up the network. Most WAPs come with browser-based setup software, including security encryption options to protect the network from intrusion. If needed, a competent computer technician should be able to help set up the network, including options for sharing your Internet connection.

Fast enough for you?

A typical 2.4-GHz wireless network will move data at 3 megabits/sec., which is faster than many high-speed Internet connections. You might prefer a 5.8-GHz network, which is about four times faster, if you plan to regularly share data between networked computers or if your network spans several miles, Getzschman says. In that case, plan to spend $1,200 to $1,500, which includes the cost of outside assistance.

“Once you get out of the 2.4-GHz consumer equipment, acquiring and setting up the equipment becomes more complex,” he says. “You may need professional help.”

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