Slashdot Mirror
4km WiFi Range w/ $5 DIY Antenna
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.
when his site gets slashdotted... in the first 25 seconds of the post.
All he needs now is a signal to pick up. {laugh - it's funny}
OS/2 - because choice is a terrible thing to waste.
If it was omni-directional, then I'll be very impressed, but you can make a pringles antenna for very cheap, and get about 10 miles range (line of sight).
The best way to predict the future is to invent it. -Alan Kay
There was a story about freecache, but no one here on slashdot ever uses it in stories. Here's a pre-cached link, in case the main NZ server goes up in smoke. http://www.freecache.org/http://www.usbwifi.orcon. net.nz/
Still, impressive gain for $5 worth of parts. Makes me wonder what I'll get if I can ever find the right connector for my Linksys wireless router to hook it up to standard coax and a pizza dish I took out of a dumpster.
SJW: a person who perceives an injustice, and while correcting it, commits a greater injustice.
http://216.239.51.104/search?q=cache:J2uZj8M2NAQJ: www.usbwifi.orcon.net.nz/+spider+skimmer+mesh+scoo p&hl=en
General Tso's Access Point.
The only acceptable defense of scientific results is to say that they were the product of the Scientific Method.
it has other uses as well. If you wrap your head in this spider silk mesh it is even more effective at blocking the evil thought control waves than tin foil!
I wonder if there are hidden shortcomings to this technique. If it only costs $5, I would think that manufacturers of wireless access points would have implemented this a long time ago (or at least made it available as a $40 add on). After all, there *is* a market for it, and at least some people would buy such a device.
Ok, did anyone grab content before it went up in smoke?
---- Booth was a patriot ----
How much does the antena cost that increases your site bandwidth?
in bed.
This site shows what's commercially available, but gives no price. Does any fellow slashdotter have a clue about exactly how much money has been saved?
_________________
distract free online advertising
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).
Am I part of the core demographic for Swedish Fish?
http://www.stanford.edu/~jstockdl/tmp/usbwifi.orco n.net.nz/
...
Mirrored as much as I could of the images before the server was smoked.
-S
**AA: a bunch of mindless jerks who'll be the first against the wall when the revolution comes
Good to know some people are still trying to improve technology remembering that not everybody has 1 trilion dollars a month to spend on over-priced gadgets.
Good work!
Site is having a slashdot effect.
You need to tell these people that you are putting their site up for brute force test before doing it so, so that they can buy some akamai bandwidth (questionable how effective it is lately though) <grin>
__________
The more I know people, the more I love animals
Piece of number eight wire reputation.
Hmm, now I feel sadly parochial.
In theory for a transmitting antenna, there is no limit to how much gain you can get. Gain is the ratio of received power to the power you would get with an isotropic radiator. To get gain, you just focus the beam tighter. The limit to how tight you can focus the beam is set by the aperture of the antenna. The gain of a receiving antenna is set by its effective area. Gain isn't hard to get.
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.
I lived in Wellington, New Zealand for a while, and I sure hope this guy is using this to steal access from somebody else, not to share his bandwidth with other people. Internet connectivity was very expensive down there, and metered (we had dsl through Telstra). Even the much-hyped CityLink wireless service is pay-as-you-go. But with his $5 setup, this guy can scan around his neighborhood until he finds somebody with an open network, and presto! Free 'net access.
Someone sent up us the Slashdotting
The super cantenna 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
How about a Freecache of the mirror?
Just think what one could do with an EMP blast (electro-magnetic pulse) discharged in the focal point of the chinese spider mesh thing.
(just kidding)
But those cost more than a cheap router and some cookware. And aren't quite as geek cool.
I've been having trouble getting an exact definition of Line of Sight. This means you have to actually be able to SEE the remote side with nothing in the way at all? I don't know how useful a 10km range is if you need that type of LoS.
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 of the earth, etc..) Do you have any idea? We'd like to do it for under a few hundred bucks each.
Is there some sort of amplifier you can get? Maybe that with a directional antenna pointed at each other? I am not concerned about FCC regulations at this point.
- It's not the Macs I hate. It's Digg users. -
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.
My sig is blank, I typed this by hand.
"Chinese parabolic cookware"
OMFG is that funny.
- Zav - Imagine a Beowulf cluster of insensitive clods...
I believe in this case Line of Sight just means you need to point it at the transmitter, you don't actually have to see it.
I just took a long car trip, relying mostly on (purchased and municipally provided*) 802.11 access, and in preparation for that trip bought a highish-end 802.11 card and extrernal patch antenna, which indeed came in handy.
:)
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!
jrnl: http://tinyurl.com/c2l8yr / foes: http://tinyurl.com/ckjno5
Yes it does. I've been accessing my Apple base station sitting in my apartment in San Fran from where I work in Oakland for YEARS now. In fact, I even access my base station from AIRPLANES while flying overhead!!!! Apple is THAT GOOD! Obviously you don't use Apple so you wouldn't understand. So SHUT UP.
He got about 17 dB signal improvement for about US $5 in materials.
I will finally get a good connection from the living room!
No matter where you go... there you are.
I live in the SF bay, what's your SSID? I find it hard to believe you get 14k without an external antenna.
Of course different areas have different rules, but just about everywhere there are restrictions on antenna gain and power for 802.11. Especially if you are not a licensed amateur radio operator.
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.
The ratio of people to cake is too big
Not political dangers, not legal dangers, but health risks. This is an unshielded piece of metal that's surely producing signal all over the place. Wi-Fi is microwave radiation. While it's not a big deal for the tiny antennas in cards or bigger antennas that are found on access points, when you start boosting the gain and have directional focus, it's critical for your long-term well being to not spend extended periods of time (or, for higher-gain antennas, any time whatsoever) in the "blast" of the beam. There are well-documented health risks from microwave radiation exposure but only at high levels and short distances.
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.
Freelance tech journalist for the Economist, MIT Technology Review, Macworld, and others
Unfortunately, Line of Sight means a direct line from the transmitter to the receiver, with nothing in the way. Trees and vegetation really attenuate the signal, and buildings are almost impossible to get through with basic off-the-shelf wireless equipment. Some people have problems just getting a signal through to their basement.
I moderate "-1, Fool"
that is:
2.385 miles (4km)
Practically speaking, the two antennas have to see each other with very little obstruction. Some materials are transparent to RF but not to light. Therefore, you can get a signal through bricks and drywall. Stuff that contains steel (like office buildings) or water (like trees) is quite lossy.
At three miles, you don't have to worry about the curve of the earth as long as your antenna is about six feet above ground level. Local topography has a much greater effect at that range.
There are a couple of things you could try even if you can't get line of sight. The cheapest might be to use quite directive antennas and bounce the signal off a tall building. (This isn't quite like reflection. You are relying on metal objects to re-radiate your signal.) You could try some kind of TV booster amplifier (they are very broadband) and hope for some scattering but I think that the multipath interference would thwart you.
The most reliable solution is to have a buddy in a tall building set up a link with each of you and do a relay.
PS. Even if you aren't worried about the FCC, they will quickly find you if you cause interference. Forget the big power amplifier!
If he is getting that kind of gain from the scooper, imagine if he used the wok...
Any particular reason you're so touchy?
-Lucas
What? No way.... with my airport I can't a signal in the park across the street, much less 14 km
I live in the SF bay
Are you a fish? Doesn't it get cold out there?
And, what kind of waterproofing do you use for your system?
OK, I guess I don't understand how wireless works.... obviously a laptop with this setup can transmit signals farther, but how does it receive a WAP's relatively weak signal? Wouldn't the WAP need to boost its output in order to reach something 4 km away?
Not only do you need to be able to see the receiver for line-of-site, but you actually need to have a sort of cigar or sausage-shape area, with the diameter at the center being measured in meters, with no obstructions. That is, merely being able to spot the receiver through the gap between a couple of tree branches won't do.
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..
Could you point me to what combo cisco product/antenna would give me a 25 mile range spot? I'm interested.
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 tell you otherwise.
For something that actually *does* work, have a look at Super Cantenna --- that one *is* the right size for 2.4GHZ, and it *is* reflective, and it *is* a waveguide and it *does* work. USD$20 for an actual tuned waveguide antenna beats a cardboard tube laced with monosodium glutamate anyday!
I find your ideas intriguing and I wish to subscribe to your newsletter.
For any wireless signal, you have a series of variables that you juggle to figure out what the maximum distance is. I don't have the formula with me to tell you exactly what it is, and I haven't done anything with it for about two years.
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 enough gain, but that's not the case. If you have more than about 40 dB of gain, you'll get a lot of feedback.
---
ECHELON is a government program to find words like bomb, jihad, plutonium, assassinate, and anarchy.
Once you've connected to the network, you'll just need to connect again in an hour or two.
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... :-)
I find your ideas intriguing and I wish to subscribe to your newsletter.
Since old dishes are about free, how about replacing the LNA with one of those same sort of external wifi transceivers?
Anyone try such a thing?
---- Booth was a patriot ----
You cannot receive more power than was sent. So there is a clear limit to gain.
Snipped from some site:
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 gain, the transmitter power output must be reduced by 1 dB.
My comments below:
In Canada:
The maximum EIRP is 4 Watts for both point-to-point and multi-point networks with a maximum of 1 watt from the transmitter.
Meaning:
In the US, Point to point links have a distinct advantage.
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.
I find your ideas intriguing and I wish to subscribe to your newsletter.
"Please Lord, Bend all known laws of Existence for my convenience. Amen."
I usually say the U.P. before major router upgrades, or other potential risky feats of Network (or System) engineering. So far so goo%*(S*(ASDF NO CARRIER
Would an old satellite dish work for this? I notice that DirecTV dishes are quite shallow, so would this be a problem.
You can get a used DirecTV dish pretty cheap.
It's true that you can't get more power at the receiver than you sent. That's not what gain describes though.
When you are talking about antennas, gain describes how your antenna compares to a reference antenna. For a transmitting antenna, the reference antenna is an isotropic radiator. For a receiving antenna, the reference antenna is a dipole.
IN THEORY, an infinitely large antenna focused at infinity has infinite gain! (The antenna has to be that large to create a beam width of zero degrees.) The signal strength from an isotropic radiator is zero at infinity. If my infinitely large antenna will produce a finite signal strength at infinity then my gain is infinite.
The most I can find is their Airport Extreme (God I hate that word)
Yes, Apple is indeed a dirty word.
Sendmail is like emacs: A nice operating system, but missing an editor and a MTA.
The SSID is YHBT_YHL_HAND.
Actually, a lot of products have really long ranges -- right out of the box! I got a Linksys WiFi router and it seems like I can pick up my SSID "linksys" network all over the place!
Heh heh..
It's based on the prism chipset, for which a variety of excellent Free Software drivers are available. Heck, you can even run an access point or WDS repeater with this dongle... See http://hostap.epitest.fi/ for more information.
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 a two way connection?
Is there a water tower or some other large structure you can bounce a signal off of?
Stop the world; I need to get off.
Sure, two Cisco BR350 series bridges with the 21dBi dish style antenna's. Cisco doesn't sell it certified for more than 15(?) miles or so because to get longer you have to get a high tower to overcome curvature of earth issues. Legally you can't go over 20 miles without going over ERP limits but you CAN run them at 100mW and get significantly more than 35 miles. You can download their calculator here, the last worksheet is the old calculator which will allow you to do all sorts of calculations which aren't necessarily withing regulations.
There are 4 boxes to use in the defense of liberty: soap, ballot, jury, ammo. Use in that order. Starting now.
How much roughly would it go up by doing this mod?
If I do this mod I 'd make sure I unplug it before I leave the house. I wouldnt want it connected during a thunderstorm.
Unfortunately, not really =( There's a lot of trees. On the good side, there's a country club and a park between us, so there's a lot of empty fields. On the bad side, the trees are very tall and there's a hill near my friends' house that's pretty tall.
I don't know if there's much I can do in this situation.
If there were a commercial product with a resonable price I'd consider it.. but the few that I've looked at cost over $1,000 on each end for both the box and the antenna.
- It's not the Macs I hate. It's Digg users. -
Looks like someone else pointed you at the right gear, the 350 bridge + dish will cover 25 miles without a problem as long as you have excellent line of sight and good elevation on both ends.
My sig is blank, I typed this by hand.
"Ye cannae change the laws of physics, laws of physics, laws of physics. Ye cannae change the laws of physics, laws of physics, Jim."
:)
And who are we to argue?
You won't be able to make this work at microwave frequencies. Directional antennas and amps simply won't help. UHF or VHF frequencies might work, however the lower the frequency you use, the more precious (and scarce) the bandwidth becomes.
Once the FCC's new vision for reusing TV channel bandwidth for wireless networking becomes reality, you'll be able to buy equipment that will probably do 3 miles via ground wave propagation just fine.
In the meantime, your options are very limited. You could buy two old Metricom Ricochet modems and run PPP between them (slow!). Since you said you don't care about the FCC, you could build your own equipment, but if you knew how to do that you probably wouldn't have asked us. If the two buildings can see a common point, perhaps you could place a solar/battery-powered wireless repeater there.
Or, do what everyone else does and set up an IPSec tunnel over the Internet.
I work as a systems engineer for a cisco partner, I really hope we land a long range bridge project. Aligning bridges at 20 miles sounds like it would be a fun challenge.
My sig is blank, I typed this by hand.
i'm working on a more compleate mirror. I allready have more and it's going to 500B/s http://defragfourms.cti.depaul.edu/www.usbwifi.orc on.net.nz/
If you could get a series of those antennae going within range of each other so they could do relay/boosting you might build yourself a nice little community wifi network.
Get a cell phone to link into that network and use VoIP and you got yourself a nice lil commodity. Hell, who wouldn't love to drop the uncalled for high rates of cell phones and benefit from VoIP cell phone calls from WiFi?!
Of course then the group of major cell companies that own the FCC would lobby to take away freedom from creativity...but it could be a fun project for a geek with the time and money. Unless you live in a country not as fucked as America.
Yea, we have an openvpn over the internet now. But cablemodems are so dismal with their upstream (256k) and we'd like to achieve better speeds then that. We don't need 54 mbits, 2 would be great.
Well, thanks for the info. We're going to keep looking and maybe we'll find something that might work. I need to get on the roof and see if we have any common points we could maybe use.
Boy, if you live in the city I bet this is easy shmeezy.
- It's not the Macs I hate. It's Digg users. -
As cool as this antenna is, it isn't very expensive to buy a nice prebuilt wireless antenna these days. Pacific Wireless dishes, 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.
Actually your RF link budget is the reason that adding a signal booster to your access point doesn't alway get you as much of a range improvement as you'd expect (it only helps performance in one direction)
Using high-gain directional antennas/woks/pringles cans/whatever is a vastly better solution for range-extension, since it enhances communications in both directions. Although aiming a high gain antenna at *just* the right spot over a large distance can be an exercise in frustration.
You are aware, I assume, that, an hour later, he'll just have to stab himself in the face again.
Nice point about the modularity, but if you did want to swap 802.11b for a 802.11a transciever you'd need to change the design as the frequency (and hence wavelength) is different.
Nope wrong again...
Gain wrt an isotropic antenna: dBi
Gain wrt a dipole antenna: dBd
Whether they are RX or TX has nothing to do with it.
The "Cantenna" I know was sold by Heathkit. The impedance match at 2.4GHz is poor, and the gain stinks--the signal is about what you'd expect from coax cable leakage. But it can handle 1KW if the duty cycle is reasonable, and it really reduces the likelihood that anybody will intercept your data.
Or - use a fast pulse-forming network to blast the signal out of an old primestar dish at 1 kW!
(Like the folks at Voltage Labs)
100mW eirp is all that's allowed. This limits the maximum legal range to around 2, 2.5km.
Or I suppose there's the possibility of using different antennas for transmitting and receiving; Parabolic receiver and an omni transmitter.
Government of the people, by corporate executives, for corporate profits.
Damn it! Does this mean this situation is impossible to get an 802.11 signal through?
:)
- Two houses, separated by a distance of roughly 50 metres
- One intervening house in the direct route seems to completely block any signal
- There is line of sight from the garden of one to the garden of the other, but:
- there are intervening trees
- approximately 5m of cable would be required on one end of the signal
- approximately 1m of cable would be required on the other
I've tried experimenting with directional antennae (of the traditional pringles-tube design) with no luck, but so far haven't invested in any low-attenuation cable for the project (was using old 10Base-2 ethernet cable as a proof-of-concept).
I don't mind what the reception quality's like, as long as it works (1Mb/s is more than adequate for the application I had in mind).
Any suggestions? Would bouncing the signal off the row of houses opposite (adding about 60m to the signal path, but substantially reducing the volume of tree involved) help? Would passing traffic cause packet loss? Is there another way?
Would really appreciate any help offered
I can't believe it! I work at the chain (DSE - dse.co.nz) that the mentioned WiFi adaptor came from (It's a Zydas that we rebrand).. In fact, I work at the branch on Vivian St, Wellington where Stan (one of the guys involved) actually bought those.. One of our best customers.
/. :)
Never thought I'd see something local on
Now THAT is funny!
OK, so I live in an area with very poor mobile phone reception.
Would this work with my mobile phone - if i made a cradle for it to sit at the focal point of the antenna, looking out of the window somewhere? Using my bluetooth headset to make calls?
That would be very useful.
Changing the directionality can also be useful in _reducing_ gain for unwanted signals. Some other wireless source is walking all over my household bandwidth at intermittent and invariably inconvenient times. I suspect a telephone. Perhaps one of these antennas will help.
"Will future ages believe that such stupid bigotry ever existed!" -- Ivanhoe
... seem to have this type of technology sorted (link includes nice photo of mountain range).
I was involved with the installation and testing of the woktenna. This is the dish style antenna on the wifi site (I took the picture of it on the pole on the roof), NOT the skimmer one. I note the author of that site has made his own woktenna since. I have also got other close up pictures of it (if they are needed). Three other miscreants are involved with this plot :)
A few stats:
The antenna has a biquad element mounted at the focal point of the dish, and the biquad element does not have the backplane reflector installed; just the 'bow-tie'. It is soldered directly to the cable connector via copper tubing, which is mounted in a hole at the back of the wok.
The distance this is currently working at is around 4 or 5 kilometers (have not tested further yet). Connections are a uniform 11mbit, and throughput (FTP) to the acess point FTP is 600 kilobytes a second or more. Ping times of less than 5ms. Netstumbler reports a SNR of around 27, signal strength at the AP is around -90dB. The wifi card in use is a Dick Smiths (www.dse.co.nz) xh8135. IIRC, some 35mW.
Previous aerials at the site included a ~15 - ~17dB BiQuad, and a Helical of simular gain mounted around 2 meters up from the roof of the house, and some 10 meters of 0.1dB/meter loss coax. The sigal with the helical was unusable - often dropping out. The Biquad was better, but only providing about 30k/sec throughput (signal strength about -98 - -99dB).
The Wok was fantastically better.
*I* currently use a short helical, and am perhaps 2km from the AP; I get maybe 550k/sec throughput. Both of us have line of sight.
We are all part of the wifi proto-network at http://www.oamaruwireless.com.
Once the FCC's new vision for reusing TV channel bandwidth for wireless networking becomes reality, you'll be able to buy equipment that will probably do 3 miles via ground wave propagation just fine.
Though cables and pipes through the ground will not help matters... There is also the issue protection against lightning or faulty power cables.
Practically speaking, the two antennas have to see each other with very little obstruction. Some materials are transparent to RF but not to light. Therefore, you can get a signal through bricks and drywall. Stuff that contains steel (like office buildings) or water (like trees) is quite lossy.
With bricks or blocks it depends very much on the brick/block in question. Also drywall partitions can use steel (rather than wood) framing. The only real option is to try and see if it works or not.
Just one comment.. Before you start tossing the 'too many people killed with guns', please keep in mind that the majority of people that are killed by guns are either:
A - Legally possessed and used in self-defense
B - Illegally possessed and used in a crime.
So changing the law-of-the-land would only prevent the honest citizen from exercising the *right* to defend themselves. It wont prevent criminals from doing harm as by definition they don't care about the law.
---- Booth was a patriot ----
Line of sight - It is not just sight as in if you shot a laser beam it would hit the target. Rather, it is defined by the clarity of the Fresnel Zone. Radio waves do not travel like a laser beam as they are in a "wave" pattern.
There exists an area above and below the straight line between two points that cannot have excessive blockage. The shape to imagine is like an eye as it tapers down on the two end points and gets very big in the middle.
For short distances, this isn't significant. It is when you start breaking the half-mile to a mile range that it gets interesting.
I remember that there used to be a calculator somewhere on Cisco's website that would calculate the size of the Fresnel Zone based on distance (it grows), but I am too lazy to look it up.
Yesterday's hit tally on the secondary site: 26 May, Wed 43438
now if only i could douple the data capacity of ...
my USB mem-stick with the wok
OK, what is the effective area of an isotropic antenna? It's zero. Therefore, an isotropic antenna cannot be a RX antenna since it would receive no signal.
An RX antenna gets gain by having greater effective area. It doesn't get gain by being directional (In the case of an RX antenna, its directional characteristics are all about S/N ratio). A TX antenna gets gain ONLY by being directional.
It does indeed matter if they are RX or TX.
LOL, I can see your network right now... nice porn btw. I also see "airport" wonder if thats his?
=1000101
Yan Can LAN!
Cringely got his wi-fi bounce past a mountain. If the hill near your friend's house is high enough, and the owners are agreeable you might be able to do something like he did.
0 7. html
Here's a low-tech non-clickable link. Check out the "Links of the week" in this article for the design guides he used.
http://www.pbs.org/cringely/pulpit/pulpit200202
Stop the world; I need to get off.
Those aren't pieces of "Chinese parabolic cookware," as the author describes.
They are ancient Ming Dynasty era signalling devices created by unusual wizards. Dontcha know the Chinese invented everything first?
They were used to signal the mother planet before knowledge of their operation was lost through the depths of time.
They were simply designed to resemble cookware in order to protect the important secret from marauding barbarians.
I placed my cell-phone at the focal point and orient in the right direction - I now get cell service in the concrete bunker of a building that I work in.
I see about a 10-20% increase in signal strength. Need a beter way to hold phone in focal point - currently using a specially configured coat-hanger.
in case you worry about practicality - I have a t68i so I can leave the phone in the dish and communicate via bluetooth - ie I don't have parabolic cookware/coat hangers sprouting from my head.