Hack 43 Add-on Laptop AntennasImprove the range of your laptop with an add-on antenna. Possibly the most frequently asked question at any wireless user's group is "how can I make it go farther?" The single most effective means for increasing your range is to add antenna gain. Most people think of adding an external antenna to their access point, or replacing the existing antenna with one of higher gain. While this can help all of your wireless clients, most people ignore the need for a good antenna on the client side. While some laptops (such as the Apple iBook and Sony Vaio, to name two) ship with antennas embedded in the laptop screen, many people are using add-on wireless cards.These cards leave an annoying little "lump" sticking out of the side of the laptop, parallel with the keyboard, and very close to the table top. This is the laptop's only antenna, and in most cases it can be greatly improved on.Not all wireless cards accept external antennas. Some (like the Zcomax XI-300 and Proxim RangeLan-DS) have removable antennas, allowing removal of the little plastic "lump," and will accommodate two external antennas using Pigtail adapters[Hack #66]. Others (like some Cisco and Senao/EnGenius cards) have no internal antenna at all, and work only with an external antenna.Adding an external antenna to your laptop has two important effects. First, most antennas have much higher gain than the tiny dipole antennas contained in many wireless cards. Second, and possibly even more important, an external antenna brings the signal away from the desktop and the body of the computer, giving it more visibility, and making it easier to relocate to find the best possible signal.While adding a proper external antenna will almost definitely increase your range, not all antennas are especially convenient. Here are three popular antennas that are quite small and unobtrusive.Poynting (http://www.poynting.co.za), a South African antenna manufacturer, produces a number of inexpensive antennas, including a 3.5" square, 8dBi sector. It sells for 176 South African rand, or about $22 U.S. It is small enough to Velcro to the back of a laptop, but offers surprisingly high gain for the size (and price). You can see it online at http://www.poynting.co.za/antennas/ism_24ghzsinglepatch8dbi.shtml.If you use a Lucent/Orinoco/Avaya/Proxim card (or a derivative, such as the AirPort), then you might have luck with the Orinoco Range Extender. It is still a bit overpriced in my opinion, selling for about $65. It looks like a rectangular white popsicle stick with a heavy rubber base and long feed line, and is advertised as a 5dBi omni. If you need more gain, the Deep Dish Cylindrical Reflector design [Hack #70] works quite well with the popsicle stick. The base is nice for sticking the antenna on a nearby table or shelfbut best of all, it is easily detached from the antenna. The stick on its own is very portable, and like the Poynting patch, is well suited for a slab of Velcro on the back of your laptop LCD. Some have even cracked it open, trimmed and re-soldered the feed line, and glued it back together again to make the perfect length of wire (and cut down on unnecessary cable loss.) The Range Extender is available from http://www.proxim.com/products/all/orinoco/client/rea/indexl.Finally, if cost is an issue, you might consider recycling a discarded "rubber ducky" antenna from a WAP11, WET11, Cisco 350, or other AP. These are small, rugged black omnis or dipoles that offer 3 to 5 dBi gain. Some antennas even sport right-angle elbows. A simple adapter or pigtail will let you use these low-gain antennas with your laptop, which is certainly better than leaving them to collect dust in a drawer. Pick a pigtail with as much flexible feed line as you need, and connect it to your laptop card. As always, be sure to check on the type of connectors you need for both ends of the pigtail (both the laptop card and the antenna will have unusual connectors). When in doubt, see [Hack #65], or check the manufacturer's specs online. |
لطفا منتظر باشید ...
