I just got an Alpha AWUS036H 1000W Hi-Gain WIFI Adapter through Amazon ( http://www.amazon.co...duct/B002BFMZR8 ) mainly to be able to be able to get access to our farm WIFI network from a Panasonic Toughbook in the field running Linux and also to be able to use the laptop as a WIFI hotspot in emergencies/disaster response. Specifically, we want to be able to use WIFI to stitch together Rural Neighborhood Watch activities when the cellphone/phone networks might be down. We are replacing an old Netgear 802.11b/g PCMCIA card.
The package I got cost $39.99 and came with two removable antennas, one 9dbi and one 5dbi, both omnidirectional. Overall, I am flabbergasted by this product: it has exceeded my expectations in every way. Various statements by the manufacturer told me to expect reception from up to a mile or more. I have made connections at almost twelve miles (perfect terrain) and sustained them at well over three.
One of the reasons I went with Alpha is that they claimed to support Mac OS X and Linux out of the box, and this was true. I simply plugged in the cable on the Linux laptop and I had a connection; the same went for an older MacBook. No drivers, hassle, or configuration.
The Linux laptop was a Panasonic CF-29 Toughbook (mil-spec rugged laptop) running Fedora Core 13 (just upgraded to FC 14). I use the Gnome Desktop's network management applet. The MacBook is running Macintosh OS X 10.5.8. We do not have any Windows machines to test on.
This is a USB-based network adapter. The product is a small device (the size/weight of a deck of cards, roughly) with a detachable USB cable, a detachable rubber-duck antenna, and a clip-mount for attaching to your laptop or a vehicle window. To install, you attach one of the two antennas, slide the NIC into the clip mount, and plug in the USB cable. The angle of the antenna is adjustable so you can set it on a table next to you or suction-cup the device to the window of a vehicle or building.
The device supports 802.11b/g (up to 54 or 108 Mbps depending on the access point). It does not support Wireless N. I did not find this much of a limitation.
Testing and Use
Again, the device powered up and established a network connection immediately. The access point here is a recent Cisco/Linksys Wireless N router (which also supports 802.11b/g) and we have a Linksys WRT-54G 802.11b/g router we use as a repeater (to extend the network coverage). We have lathe-and-plaster and lathe-and-wire walls in the old farmhouse which often degraded the signal from the older PCMCIA wireless card. Alpha's adapter shows full signal strength with the smaller, portable antenna everywhere inside and over most of the 10-acre property. Signal is significantly degraded inside the tin-side pole barn, but that is no real surprise.
What was a surprise is when I suction-cupped the larger 9-dbi antenna to the outside of the passenger window on the truck and went for a drive up the road. The included USB cable was nearly too short for this use. The manufacturer recommends using a USB extension cable to add a bit of reach for better positioning of the antenna. The metal shell of the truck does degrade the signal, so it is better to have the antenna outside. When I did this, we could get a signal from the Cisco/LinkSys router with its dinky internal antenna from nearly the nearby Interstate. When we got to high ground on the Interstate, I immediately picked up 23 separate networks from this rural area, one of the routers I know to be at least 12 miles from that point and I connected for a short bit to a router from a hotel in a neighboring town (perhaps 8 miles). It was very difficult to maintain a solid connection while moving (and I was reluctant to leave the antenna suction-cupped at highway speeds...), but when well-positioned on good terrain, the device is amazing.
The external antennas provided are compatible with the WRT-54G's removable antennas, so I am in process of ordering two more of the high-gain antennas with magnetic mounts to put on the WIFI repeater mounted on the farm house tin-roof. I expect to be able to establish connections with neighbors between three and five miles away for Neighborhood Watch purposes. Our cell phones are WIFI-capable and have an android Push-To-Talk program called VirtualWalkieTalkie ( http://www.androlib....alkie-pCBE.aspx ). I can run a local Java-based server for this from the ToughBook and then the phones can connect to each other even if the cell network and local (satellite) Internet connection is down (but we usually use handheld FM radios for local voice communication). Both the access point and the Toughbook will readily run off of 12-volt power from our battery bank, so then, we can access emergency documents, transfer photos (of, say, a damaged building or a suspicious vehicle) over a several mile radius, with the Toughbook running off of the vehicle power and providing a local access point/repeater. The Alpha hi-gain adapter basically provides an inexpensive glue for an ad-hoc rural network which would otherwise require much more expensive equipment. Because WIFI is industry standard, we can tailor the software on top of it to our needs.
Battery usage is noticeably increased when using this device, though not as bad as I thought it would be. Typical life for me has gone from 5-6 hours per charge to closer to 4-5. It does, however, seem to suck power even after putting the laptop to sleep or hibernation, so I have gotten used to unplugging the USB cord when I do not need it.
Two words of warning, however:
You can connect to an access point from much farther away than you can meaningfully transfer data. I have connected to some distant access points in testing at two-three bars of signal strength (several miles away) and had very bad transfer rates, I think because of dropped packets. It seems to be related to the quality of antenna/receiver on the access point you are connecting to. If you have a crappy antenna on one end, the Alpha can only do so much, especially with intervening obstacles. Good terrain, few obstacles, and a decent access point on the other end gives consistent transfers even miles away.
Being able to access the network from a long distance away does not do away with traffic congestion. If your network is suddenly accessible over a large area, you can overload it with too many simultaneous users. It works better for our applications therefore in a rural areas where you have a small number of users spread over a large distance as opposed to an urban area where you have dozens or hundreds of users within a mile or two.
In any case, I would definitely recommend this product and second the opinions of some other reviewers that the more powerful 2000 mW version is simply not necessary. This one has all the transmitting power for the job and there is no need to waste battery-life with more. The difference between the 5dbi and the 9dbi antenna or in better antenna positioning seems to be much greater than the difference from adjusting transmitter power at either the adapter or the access point. Hopefully, I will convince folks in the county to buy a number of these little devices.
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