NOTE #1: This is a lengthy article that will be published in three installments over the next few days.
NOTE #2: This article contains a number of pictures. You can view larger images by double-clicking on any picture.
NOTE #3: Part #1 of this article is available at http://rv.dickeastman.com/2012/01/how-to-build-a-long-range-wi-fi-system-part-1.html
NOTE #4: If you did obtain a TP-Link 2.4 GHz High Power Wireless Outdoor CPE Model TH-WA5210G as described in this article, you may be interested in my follow-up article, Configuring the Outdoor Access Point at http://rv.dickeastman.com/2012/11/follow-up-how-to-build-a-long-range-wi-fi-system-configuring-the-outdoor-access-point.html
I purchased a commercially-built router that includes the router and antenna, all built into a weatherproof box. It even sends power to the router through the same ethernet cable that sends computer signals. The router picks up wi-fi signals and sends them through the ethernet cable. This router is a 2.4 GHz High Power Wireless Outdoor CPE Model TH-WA5210G manufactured by TP-Link. ("CPE" stands for "customer premises equipment." This unit is designed for installation in a customer's home for use on city-wide wi-fi networks.)
Similar units are made by a number of other manufacturers. I would suggest using a high-powered device of 500 milliwatts or more. Some hobbyists have obtained great results by placing Linksys or other routers designed for indoor use inside Tupperware or similar containers to protect them from weather. The box will need holes for antennas and signal wires. Once the connections are made, the holes can be sealed with any weatherproof sealant made for the job. Linksys WRT54G-series routers are especially popular amongst hobbyists who wish to install long-range wi-fi systems. This $60 router is easily modified in many ways, especially if DD-WRT software is used. Perform a Google search on "Linksys WRT54G" or "DD-WRT" for details.
At first, I planned to use the Linksys WRT54G. However, I figured I needed to spend about $60 for the router, a few dollars more for a Tupperware container, still more money for some sort of system for sending power to the unit on the top of the telescoping mast, and a dollar or two for sealant. I also needed to cobble up some method for mounting everything on the mast. I then discovered that Amazon sells the TP-Link TL-WA5210G for $60, including weatherproof container, mounting system, and a power-over-ethernet device. Even better, Amazon offered free shipping. I went with the Amazon offering.
I have also seen similar units advertised from Ubiquiti and have heard good things about them. However, I have no experience with the Ubiquiti devices. You can learn more at http://goo.gl/7YK9n.
You can also find many interesting looking weatherproof wi-fi devices by searching on eBay. However, don't ask me for advice! I have never tried any of them other than the Model TH-WA5210G manufactured by TP-Link.
The unit I purchased has a built-in antenna but also has a connector for use with external antennas. So far, I have only used the built-in, high-gain antenna and have found it works well when installed on the telescoping mast on the back of the motor home. I haven't found a need for an external antenna. However, if I was trying to establish connections over even longer distances, such as between two buildings located several miles apart, I might want to use external Yagi or parabolic dish antennas or something similar.
Keep in mind that the new router needs to operate in the opposite direction to the typical wi-fi router installed in your home. In-home wi-fi routers normally accept incoming ethernet signals from the phone company or cable company; then they convert those signals to wi-fi that can be sent by wireless to multiple computers in the home. In the case of my RV set-up, I needed a device that accepts wi-fi signals and converts them to ethernet. It is similar technology to an in-home router but is designed for the opposite purpose.
Regardless of the router used, I have to specify the wi-fi network to be used. Whenever I move to a new campground, I have to go through the router’s configuration menus again to give it the name (SSID) of the new network. I generally use either the computer's wi-fi software or a wi-fi-equipped cell phone to find the local wi-fi network(s) and then use the TH-WA5210G's configuration menus to specify the one I want.
The Model TH-WA5210G manufactured by TP-Link has a built-in directional antenna, which is simultaneously a good and bad thing. The good thing is that directional antennas typically produce higher gain, which results in stronger signals over longer distances. The drawback, however, is that they have to be aimed to point in the direction of the desired wi-fi hotspot. Sometimes I can ask when checking in at the campground, "Where is your wi-fi hotspot?" However, if connecting to an off-site hotspot, I have to investigate further.
The answer will be obvious if the hotspot's SSID says McDonald’s or Starbucks or a similar brand name. Just look around for that location. However, connecting to other locations may be more difficult.
The TH-WA5210G manufactured by TP-Link has small lights on top of the unit that display signal strength. It is easy to keep an eye on these lights while manually turning the antenna 360 degrees. Leave the device pointed in the direction where the lights show the strongest signals. However, the lights are small, dim, and difficult to see in bright sunlight. The fact that they are now mounted at the top of the telescoping mast about twenty feet in the air doesn't help!
I have learned to aim the antenna in any direction that seems to work when setting up the antenna in daylight. About dusk, I can see the lights easily. I "fine tune" antenna direction at dusk by slowly turning the mast.
NOTE: Don't be surprised if you get questions from bystanders in campgrounds. RVers are curious. Most everyone will notice those blinking lights on that funny-looking box on top of the unusual mast on the back of your motor home! Most everyone will wonder, "What's that?" More than a few people will ask you face-to-face. It's a great way to meet your neighbors!
Finally, I will describe the telescoping mast that I use in Part #3 of this article.