4km WiFi Range w/ $5 DIY Antenna 254
Mignon writes "This industrious fellow in New Zealand made his own WiFi antenna using a USB WiFi adapter and a Chinese 'spider skimmer mesh scoop.' He got about 17 dB signal improvement for about US $5 in materials." Update: 05/25 23:09 GMT by T : Reader
John Stockdale offers a U.S. hosted mirror of the site. Update: 05/26 13:58 GMT by T : Reader Jared Mauch contributes another mirror.
Just need a signal (Score:3, Funny)
We get signal (Score:3, Funny)
Re:Just need a signal (Score:2)
I go on the occasional wardrive across parts of NZ and we get around one hundred up to two hundred APs on relatively short trips (which they usually are).
One word... (Score:5, Interesting)
Bluejack
I already built one of these things after the site first surfaced a couple of weeks ago. The neat thing about it is that it's modular insofar as your choice of radio goes. Unplug the 802.11b tranceiver, replace it with a usb Bluetooth tranceiver, aim at the nearest bus stop, and wa-la, bluejack city. Want to use 802.11g, or heaven forbid, 802.11a, plug one in! It's the ultimate in modular l33+ hax0r radio toys. Why, I reckon you could even plug an usb IrDA adaptor in there...
No, wait... :-)
What direction? (Score:3, Informative)
Re:What direction? (Score:3, Informative)
Re:What direction? (Score:3, Informative)
Re:What direction? (Score:3, Informative)
Re:What direction? (Score:5, Informative)
Re:What direction? (Score:2, Informative)
Re:What direction? (Score:5, Informative)
"Omnidirectional" is somewhat of a misnomer. Omnis transmit a pancake-shaped signal -- good signal in all directions in the same plane, but very little signal up and down. What you're refering to is called an isotropic radiator.
-jim
Re:What direction? (Score:5, Funny)
Re:What direction? (Score:2)
Re:What direction? (Score:3, Informative)
The absolute power limit is 1 watt for unlicensed 2.4 ghz equipment. The EIRP limit is 4 watts for point-to-multipoint, but can be higher for point-to-point. (Disclaimer: I'm not an RF engineer, so read the actual fcc regulations before you try it.)
more information [personaltelco.net]
-jim
comparing apples to oranges (Score:4, Informative)
The super cantenna [cantenna.com] is only 12 db. 17 is more impressive, and should result in greater range.
Range itself is hard to compare, as it depends on environment, the radios used (cheap 35 mW? 200 mW with good receive sensitivity?), whether the same antenna is used on both ends, and the subjective evaluation of what exactly constitutes a "useable signal".
-jim
Re:comparing apples to oranges (Score:2, Interesting)
Re:comparing apples to oranges (Score:3, Informative)
5 dB of additional gain at one end will give you 77% more range, all other things being equal. Adding 5dB at EACH end, and you have tripled the distance
Or, it can give you a nice punch through vegetation loss
Does anybody have reliable (or empirically determined) Eb/N0 and NF figures for popular WiFi hardware, for doing real link budgets?
Re:comparing apples to oranges (Score:2)
You can find transmit power / recieve sensitivity numbers for a lot of prism2 cards here [personaltelco.net]. I suspect most of these numbers are gleaned from product brochures, so you mileage may vary.
-jim
Re:comparing apples to oranges (Score:2)
Interesting table, although lacking in meat.
A receiver sensitivity number, without specifying test conditions, is really meaningless. Vendor A could specify a signal of -80 dBm for a BER of 10**-6, while vendor B could specify -90dBm for a BER of 10**-3. Without both numbers, a purchaser cannot make an informed decision. (This is all moot if there is a standard published test condition, perhaps as part of the 802.11 standard, which I should read, but that smacks of RTFA)
Wbat I would love to see is Eb/
Re:comparing apples to oranges (Score:2)
I can take the worst pringles can antenna and stick it almost directly on the Wifi card (1 1/4 wavelength of feedline) and beat the best home made antenna with 10 feet or more feedline and 3 connectors because of the card connector and adapter to the N feedline connector...
losing a gob of power in the feedline and connectors (almost 1 db per connector is lost at 2.4ghz)
removing losses adds up to greater radiated power fa
Re:comparing apples to oranges (Score:2)
But pringles cantennas don't work... (Score:2)
Still, placebos work on a substantial portion of folks, so if you feel that your pringles can antenna works for you, far be it from me to te
Re:But pringles cantennas don't work... (Score:2)
Re:But pringles cantennas don't work... (Score:2)
The difference between your speculations and reality is that "Pringles cantennas" simply use the Pringles can as a housing for a "shotgun" Yagi antenna. Anything which relies solely on the Pringles can will do a whole lot of nothing, but it's possible to use several different varieties of ordinary cans (Pringles, beef soup, etc) to house a good antenna.
While it's certainly better for anyone just looking for gain without any hassle to get a premanuf
Re:But pringles cantennas don't work... (Score:2)
freecache link (Score:5, Informative)
Re:freecache link (Score:2, Insightful)
Re:freecache link (Score:2)
Re:freecache link (Score:3, Interesting)
Good point about the file size - html != >5MB.
Re:freecache link (Score:2, Informative)
Re:freecache link (Score:2)
Re:freecache link (Score:3, Informative)
Already slashdotted? (Score:4, Funny)
It's not $5.00, even in your money... (Score:5, Informative)
I didn't shop around for best price, etc, etc, 'cos I knew that once this thing hit slashdot, there was gonna be a worldwide stockout on the chinese cookware. I could have gotten things a bit cheaper if I had shopped around, but short of an AUD$1200+ aeroplane ticket to Guangzhou and buying direct from manufacturers, there was no way this setup would cost $5.00 of anyone's money. With time and petrol and driving around, I guess it cost AUD$100.00. Good fun tho, and worth every cent.
Re:It's not $5.00, even in your money... (Score:2)
So now we call it. . . (Score:5, Funny)
Apparently... (Score:5, Funny)
Why haven't AP manufacturers tried this? (Score:4, Interesting)
Re:Why haven't AP manufacturers tried this? (Score:4, Insightful)
The most likely shortcoming is that it probably violates the FCC rules about how much power an unlicensed transmitter can put out.
Re:Why haven't AP manufacturers tried this? (Score:5, Interesting)
In the US I believe the output is measured by the effective output of the antenna (essentially transmitter power + gain AFAIK). This allows you to build directional antennas that can go some distance (you're also allowed a whole 1W signal which is quite a lot).
OTOH in Europe we measure EIRP, which is total power in any direction - so directional transmitters are illegal (we also only get 100mw to play with). This is why things like the WRT54G are so useful - you can have a really powerful receiver (not limited) and a still use the legal transmitter in the other aerial.
Re:Why haven't AP manufacturers tried this? (Score:5, Informative)
IIRC, the maximum tx power in the 2.4ghz band for unlicensed users is 1 watt, or 4 watts EIRP. For point-to-point links, though, you can trade 1db of power reduction for 3 db of antenna gain, allowing much higher EIRP.
More info is here [personaltelco.net]
-jim
Re:Why haven't AP manufacturers tried this? (Score:2, Informative)
Generally it's something like 3db of gain is permitted for each 1db drop in transmitter power.
So you can't just start throwing directionals off your 100mW transmitter.. you also have to attenuate it properly first.
This allows you to get directional gains, but keeps a sane limit on the total power.
Kind of... (Score:2, Informative)
The FCC regulations for Point to Multi-Point allows only 36 dBm (4 watts) EIRP. This is 30 dBm (1 watt) into a 6 dBi antenna. If you use a 10 dBi wireless antenna, you must limit your transmitter (or amplifier) to 26 dBm (10 + 26 = 36 dBm). For a 14 dBi panel wireless antenna, this allows a 22 dBm transmitter (or amplifier).
According to FCC regulations, 2.4 GHz Part 15.247 point-to-point transmitters may use a 30 dBm transmitter with a 6 dBi antenna. For a 3 dB increase in antenna g
Re:Why haven't AP manufacturers tried this? (Score:2)
Damn that was quick.. (Score:2)
Death by /. (Score:2, Funny)
How Much Do the Commercial Versions Cost? (Score:3, Informative)
_________________
distract free online advertising [seunosewa.com]
Re:How Much Do the Commercial Versions Cost? (Score:3, Informative)
Try looking at hyperlink [hyperlinktech.com], superpass [superpass.com], and netnimble [netnimble.net] for comparison.
-jim
Re:How Much Do the Commercial Versions Cost? (Score:4, Informative)
Also, to those confused about how antenna gain works. The gain is measured in comparison to the output of an isotropic radiator, basically something that puts out the same signal strength in all directions. So that means that any unamped antenna with a gain higher than 1dBi is directional in some sense, because the total radiated power is still the same. So-called omnidirectional antennas really are only omnidirectional in the horizontal plane, if you go up or down their signal strength drops off rapidly.
Re:How Much Do the Commercial Versions Cost? (Score:3, Informative)
No, +1dB gain is still gain.
I'm pretty certain that 0dB == unity gain.
It's a logarithmic scale, with negative dBs for attenuation situations. log(1) = 0
Little brain seeks big brain. (Score:2)
I am sure someone has written an app to detect incomming signal strength almost akin to passive sonar, but would you actually be able to create
Too bad it's directional (Score:4, Insightful)
I guess it's a neat hack if that's the only way to communicate with your friend 4Km away, and you only have one friend (or your one friend has a nice network connection to the rest of the world and is willing to share).
Re:Too bad it's directional (Score:3, Interesting)
An acquantance of mine is considering setting up something like this, since he can't get high-speed internet access -- too far for DSL, and the cable company hasn't upgraded his section of the network yet. However, a five-mile wireless link would let him work off someone else's high-speed c
Re:Too bad it's directional (Score:2)
I'm trying to do this with a friend that's 3 miles away. thing is, we don't have LoS. There's mostly trees between us but even if we stand on each others houses I doubt we have a clear line of sight.
Do you know what the options are? I can't exactly mount a 20' tower on the roof.
Re:Too bad it's directional (Score:2)
Re:Too bad it's directional (Score:3, Informative)
Very cool i would say...
At take a look at the node count [nodedb.com]
To these people it's very usefull.
Re:Too bad it's directional (Score:2)
But this whole line of sight thing. How are you supposed to do that? It's not like there's a grassy field between us. There's harldy a building though, it's all trees, but if you need LoS you'd need a very tall tower to mount this thing on regardless?
I'm trying to find a way to get this done without a LoS. It doesn't have to be 802.11, we just
Re:Too bad it's directional (Score:2)
I hope you have $2K laying around...
Re:Too bad it's directional (Score:5, Interesting)
Wrong. It isn't helpful unless one end point is stationary. Which is a big difference.
Case in point. I live on a fairly large property. I'm trying to extend my wireless signal to the edge of the property, where my hammock is, so I can work in my hammock. A directional antenna hooked to the transmitter on my router inside my house extends the range in whatever direction I point the antenna in, i.e. towards my hammock. Since the antenna increase pickup as well as transmit power, I just put it on my stationary router, and I don't need to do anything to my wi-fi card on my mobile laptop.
If I wanted to extend coverage to the whole property, I could aim my antenna at a distant repeater to get omnidirectional coverage from the repeater, while still increasing range from my base-station router.
Wireless rules.
Re:Too bad it's directional (Score:2)
Re:Too bad it's directional (Score:2)
Not true. My connection to home is currently wireless with a directional antenna. DSL only works over high quality phone lines. I've always wonder just how much copper is there between my house and the phone company... All place in the ground at a large labor expense.
Wireless power delivery doesn't work so well (though Tesla fans might try to claim otherwise if they don't understand exactly what his assumptions were). For most data uses though, wireless makes perfect sense.
Temporary Mirror at Stanford University (Score:5, Informative)
Mirrored as much as I could of the images before the server was smoked.
-S
Nice work (Score:5, Insightful)
Good work!
See Kiwis, we really do deserve our... (Score:4, Funny)
Piece of number eight wire reputation.
Hmm, now I feel sadly parochial.
Unlimited gain! (but it doesn't matter) (Score:5, Informative)
The bigger problem is to get line of sight. At this frequency, if you can't get line of sight, all the gain in the world won't help.
Re:Line of sight? Help me out here. (Score:2)
See, I'm trying to get a wireless connection to my friends network about three miles away, directly. We can't erect 100' towers so we're trying to figure out our options. We can mount the things on our roofs but we won't have direct line of sight (some trees, the curve
Re:Line of sight? Help me out here. (Score:2)
Re:Line of sight? Help me out here. (Score:2)
Re:Line of sight? Help me out here. (Score:2)
must be for a user, not a provider (Score:4, Interesting)
EMP (Score:2)
(just kidding)
One word (Score:5, Funny)
OMFG is that funny.
USB 802.11 dongles -- are any Linux friendly? (Score:5, Interesting)
I considered one of the USB 802.11 donglers, but passed on account of ignorance: Are any of them of Linux-friendly? Are some brands better than others? Can anyone provide reception figures or anecdotes?
It certainly would be nice to have a rooftop mount on my station wagon to which I could as necessary string up a 15' USB cable and thumb-drive-style 802.11 thing
timothy
*Thanks, taxpayers and politicians of Salt Lake City!
Re:USB 802.11 dongles -- are any Linux friendly? (Score:2, Informative)
Works pretty dang well, probably better than the Windows setup.
Re:USB 802.11 dongles -- are any Linux friendly? (Score:2)
What kind of comment is that? "probably better"? Have you ever used the Windows setup?
I use Windows XP and a Linksys WPC54G. I plug it in and XP finds the drivers.
Works pretty dang well, probably better than the Linux setup.
Re:USB 802.11 dongles -- are any Linux friendly? (Score:3, Informative)
I've been using it to access my server at home because I'm too lazy to lay cable under the house.
Syntax USB-400 802.11b USB Dongle (Score:2)
Finally! (Score:2)
I will finally get a good connection from the living room!
Please be aware of the regulations (Score:4, Interesting)
These things are unlicensed part 15 devices which have strict restrictions on power output (which includes any gain from directional antennas) and can not interfere with licensed devices like amateur radio operators.
I'll leave it up to the reader to Google for what the limits are in your area since it varies. Just remember that you can't just slap on any super-high-gain antenna and remain legal.
Dangers of this kind of ad hoc device (Score:3, Interesting)
Because this ad hoc device hasn't been checked out in any fashion, it's possible that even with it facing away from you, you could be subjecting yourself to cellular damage from the microwave radiation. I wouldn't recommend this. The cantenna design is much simpler and safer. Other ad hoc designs at least have parameters that prevent so much signal spew. This one worries me.
Re:Dangers of this kind of ad hoc device (Score:5, Informative)
To give you an example... You microwave uses 4000 times that much power to cook food with.
I would imagine if you stood in the beam path of a 20+db antenna for a couple months you would have health issues... but you also wouldn't have a signal
As health risks go a cell phone is a MUCH larger output of power and you stick it right next to your head. Worry about those first
And FWIW cantennas are no better... most directional antennas send most of their power out the front but all of them have sidelobes.
Re:Dangers of this kind of ad hoc device (Score:3, Informative)
For the freedom loving ppl of the world... (Score:2)
2.385 miles (4km)
Shouda used the Wok... (Score:5, Funny)
I seriously hope... (Score:2, Funny)
That this guy kept the other $145 he saved from building his own antenna because he's definitely gonna need it to pay his web host.
I have the site saved, so anyone want to host a mirror, let me know..
One problem with Chinese cookware antennas... (Score:5, Funny)
usb + dish network dish? (Score:3, Interesting)
Anyone try such a thing?
How About an Old Satellite Dish (Score:2, Interesting)
You can get a used DirecTV dish pretty cheap.
vs commercial antennas (Score:3, Informative)
As cool as this antenna is, it isn't very expensive to buy a nice prebuilt wireless antenna these days. Pacific Wireless dishes [pacwireless.com], for example, are about US$50 for 19dBi or $70 for 24dBi. I've used their products, and they are very nice. I've given up on building 802.11 antennas: it's too much work vs the cheap commercial antennas for me.
Re:Google Cache (Score:2)
Re:Google Cache (Score:2, Funny)
How long have you been learning that you haven't gotten to 'hyperlink' yet?
Re:Apple's had this for years (Score:2)
Re:Apple's had this for years (Score:5, Interesting)
The airport base station doesn't have a range anywhere NEAR 14km. There are lots of antenna out there for lots of base stations (including the Airport ones) that will give you that range, but Apple has not "had this for years" any more than every other vendor that sells products with the option of adding an antenna.
Hell, Cisco has products that have 25 MILE ranges, with the right antenna.
Shut up! Apple rules. Period. (Score:3, Funny)
Re:Shut up! Apple rules. Period. (Score:5, Funny)
Heh heh..
Re:Apple's had this for years (Score:2)
Re:Apple's had this for years (Score:2)
-Lucas
Re:Apple's had this for years (Score:2)
No, there's something called a "Link Budget." (Score:2)
To sum up, you can either boost the transmitting or receiving antenna gain in order to improve the distance. You can also move one or both of the antennae up - the higher up they are, the further the range.
In theory, you'd think that you could read any signal with a big en
Re:So what's to stop you... (Score:4, Informative)