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23 of 25 people found the following review helpful:
5.0 out of 5 stars
WOW! works beyond expectations!, May 16, 2009
We kinda bought this figuring it was "snake oil". Well, we were wrong...dead wrong! We plugged this into the Vista laptop, Vista found it and we were using it in less than 1 minute, and to our surprise it picked up our neighbor's router 1000 ft down the road and on the other side of his house! We used to get his signal intermittently on the laptop, but with this plugged in with the hi-gain antenna, we get 4 out of 5 bars! This is through tall, thick trees and a motor home!
When the first reviewer (I read)says it got her father in law's signal 1000 feet or yards down the road, she isn't lying!!!
I just put it on my Windows 7 desktop and it works just the same. I just plugged it in, and windows found it, installed drivers and it's fine.
I ALWAYS suggest going online for the latest drivers for any computer hardware, but this one seems to work fine off of Windows Vista and 7's proprietary drivers.
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13 of 15 people found the following review helpful:
2.0 out of 5 stars
works... Inconsistently, doesn't really work, October 5, 2009
What I bought this for, was to catch a wi-fi signal from about 20 yards away.
Sometimes it works like a phenomenon. I just have to open my window and set it on the sill and I can catch signals from 2 football fields distance and sometimes even farther.
Other times, it doesn't work at all. I can turn the antennae in any direction, up down left right slowly adjusting to try and catch the signal, even trying both antennaes provided- but don't get anything. I see the networks when using the software, but can't connect strongly enough to get any internet, not even a slow crawl.
If anyone knows of a better solution, please let me know! I've heard about the Trendnet antennaes but i have no idea what I need to make them work, wondering if I can use this unit and just attach an SMA cable to a better antennae and stick it on my roof?
This is DEFINITELY NOT the 'Strongest On The Market' as the seller's ad claims. I had a wi-fi booster that I used on my last deployment to Iraq, and could catch signal from miles away... Too bad I forgot it!!!! This one works great one day out of the week and the rest of the week there's nothing i can do to make it work!
I will say this, whenever I am standing within 10 feet of a router, it boosts the signal significantly. Works great if you are at a library or somewhere with wi-fi and fighting for bandwidth.
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21 of 27 people found the following review helpful:
4.0 out of 5 stars
The Alfa 1000mw/1 Watt Wi-Fi Wirless Transceiver is A+ but it won't always produce 1 watt of output, See why as well as advice.., February 1, 2010
Alfa 1000mW 1W 802.11b/g USB Wireless WiFi Network Adapter
This review is more for the technically oriented group who want to look more deeply into the technology but written in easy to understand terms.
From what I've seen there is nothing better you can buy anywhere right now. However, let me point out that the 1000mw/1 watt output rating might not always be true but before I start on that let me outline what I like about the unit:
1. The Wi-Fi transceiver produces far more power than what any laptop computer or external Wi-Fi transceiver I know of will output.
2. Has a "RP" or what is called reverse polarity coaxial antenna connector which allows me to use a higher gain antenna. See my notes on this type of connector further in this review.
3. Is external and powered by a USB cord allowing me to place the unit with its whip antenna at a better spot than where my computer is at, up to about 15 feet away if using a USB extension cable.
OK, to get to my question of whether the Alfa produces the amount of RF power they say it can:
I was curious if this unit could really produce 1 watt of output power, it seemed far too light weight to do that so I took my AWUS036H unit and fed its RF output into a lab quality spectrum analyzer on maximum hold to record its highest RF carrier level power output as it pulsed to interrogate a remote Wi-Fi system, which of course it couldn't while hooked up to the spectrum analyzer instead of an antenna. I was right about the lower output power, I measured the output to be about 250 mw or +24 dBm, that's 6 dB lower than its advertised power capability of +30 dBm which is four times lower output than the specified 1000mw/1 watt (The difference between +24 and +30 dBm is a factor of -6 dB which as a logarithmic power factor is four times less power). Just to be clear to the folk who don't work with decibels or dB; +30 dBm (referenced to 1 mw/milliwatt) is 1000 mw or 1 watt or +30 dBm = 1 watt.
IMPORTANT: If you have the one watt output version of this Alfa and have the dual USB cable they are now providing with the units which plugs into two USB receptacles at the same time do so! The second USB connector is needed due to the high current demand of the higher power unit, one is for data the other for more current supply to the Alfa. I did not know this and only used the one USB connector which passed both data and power and now that USB port on my computer does not work. Apparently, too much current had been drawn and damaged it. I expect there is an automatic current limitation built into most computers but in my case it did not prevent the USB port from becoming damaged. Mine ran fine for a week with just one of the USB connectors plugged in to my computer but it eventually caused that port to fail. I would have used both ports but I needed the other USB port for something else, unknowing the resulting damage that action would produce leaving me with just one good USB port on that laptop now.
Finding that my Alfa only produced one forth the advertised RF power output I figured either Alfa was misrepresenting its true output or I had a defective unit. I then went to the Alfa web site and found some specs for the unit, their specs show this unit has different output levels for different modes of modulation! For OFDM modulation the RF output is rated at +24 dBm which is 250mw or a quarter of a watt/.25 watt. When using CCK modulation the output is rated at the full +30 dBm output which is 1000mw/1 watt. So, you don't really get a full watt of output in some modes of operation! From what I've been able to find on the net regarding these two kinds of modulation is that the Alfa is rated at less power for OFDM because the efficiency of its built in power amplifier is fairly low due to requiring the amplifier to operate in a highly linear manner which is less efficient producing less output power where CCK modulation does not require the amplifier to be linear and thus more efficient producing more output power. I am still trying to determine if CCK is a short burst of data and OFDM a longer or continuous transmission which would also explain why one mode allows more output power over the other, if the shorter bursts allow the amplifier to transmit a higher peak of power without overheating. I have not found what I'm looking for on this yet, when I do I will update this review. (More on CCK and OFDM at the bottom).
According to law, in the USA when the unit is transmitting with CCK modulation (fast pulsed short duty cycle) producing 1000 milliwatts or 1 watt of output at 2.4 GHz the highest gain antenna you can legally use is 6 dBi which produces an effective radiated power (reference to isotropic radiation pattern) of 4 watts, that's the maximum power you can legally radiate which is higher than many other countries if not all. When the modulation uses OFDM producing 250 milliwatts of output the highest gain antenna you can legally connect and transmit with is 12 dBi which will produce an EIRP of 4 watts. The highest gain antenna you can legally use in the CCK mode of modulation producing 1000mw/1 watt of RF output at 2.4 GHz is 6 dBi which also produces a EIRP of 4 watts of EIRP. What does EIRP mean? It is the abbreviation for "Effective Isotropic Radiated Power" which means the combination of RF power input and gain of the antenna you are using (when measuring the area of its maximum radiated power) will equal the same amount of signal level that a antenna which radiates equally in all directions would produce when being fed with the same amount of RF power at its feed point (not counting feed line or coax and connector losses along the way to it).
If the above doesn't make sense there are plenty of web sites you can Google which better explains EIRP but in short, it just means how much signal level your antenna can produce... some antennas have such high "gain" that they can make a very low power signal seem like a very large amount of power due to squeezing most of the transmit power into a very tight and narrow bream width. In the case of a collinear Wi-Fi whip antenna which has several dB of gain the design of the internal elements of the antenna cause the area of reception as well as transmit power to be squashed down into the shape of a doughnut so that little power is wasted strait above or below the antenna and radiated outward in a pattern which is more useful for line of sight point to point communications but omni-directional as a whip.
Want more receive and transmit gain than a collinear whip can produce? Try a flat panel, Yagi or parabolic dish antenna. The flat panel antennas are really a phased array of dipoles in the form of "slot" antenna which give gain, the more which are phased together inside the panel the higher the gain and consequently the larger the panel. High gain Yagi antennas are very long and bulky, not so good for high winds but can produce good gain too. A parabolic dish or paraflector type of antenna has very high gain and is mechanically stable but the more gain you want the larger they get. As a general rule, every time you double the diameter of a dish you get six dB more gain or equal to four times more effective power output or higher receive gain, at a given frequency. Double the frequency instead of the size of the dish and you get the same, 6 dB more gain. That said, every time you double the diameter of a dish there is four times more surface area... thus, 6 dB more gain which is 4 times more power! Why? When receiving the larger sized dish is collecting more signal and focusing it into the feed point, when transmitting the surface of the dish is concentrating the transmit power into a much smaller beam width of RF power so less of it is wasted going out into directions you don't want the power to go, as a point to point antenna.
Regarding the Alfa's coaxial RF connector:
I am not yet sure why the unlicensed (not requiring a license to transmit) Wi-Fi industry did so, but the RF connectors used on their equipment are non-standard and because of this won't fit together with normal coaxial connectors. The antenna connector on the Alfa, at a distance without viewing carefully enough looks just like a normal SMA RF connector but it isn't! That connector would normally be called a female connector which you would screw a male SMA connector on to but they made a change to the center pin, instead of a female center receptacle which a male pin slides into the manufacturers reverse it by making it a stub instead of a hole, or in other words there is a pin coming out of the center. Yes, it's reversed inside but the outside looks like a normal connector. I've wondered why they did this and I could research this more but my bet is that it was a regulatory action placed on them or something the industry decided to do to make it harder for people to find ways to illegally use the equipment by hooking up high gain antennas which have the same connector, but made for F.C.C. licensed point to point communication systems. If you are breaking the law by using a antenna which has a gain which is a little too high I wouldn't worry about the F.C.C. knocking on your door too much as the agency is severely under-funded, have been for their entire history except in the hay day of CB, and don't have very many employees and very few offices which are scattered around the USA many hundreds of miles apart. There is just too much Wi-Fi for them to chase after those complaints and users are left to solve problems themselves. Of course, if you were interfering with a licensed station they could drag the F.C.C. into it but the Wi-Fi spectrum these units use is unlicensed so how likely is that to happen? It can happen but I'd expect to be hit by lightning first.
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