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O'Reilly's Antenna Shootout
nickynicky9doors writes: "From Rob Flickenger O'Reilly Network's Systems Administrator :
'Gregory Rehm hosted an Antenna Battle Royale between a Lucent popsicle stick, a couple of Pringles Cans, our Coffee Can, a Hunt's Tomato Sauce can, and a 40oz can of 'Big Chunk' beef stew. Who was the winner?'" Let's just say it doesn't come loaded with saddle-shaped styro-chips.
the lucent popsicle is nothing more than a 5/8ths wave antenna.. signals not at the horizon will suffer (up.down)
The pringles can is nothing more than a basic beam.. 1 driven element and 1 reflector (the metal bottom) it is not acting like a waveguide because the "metallic substance" is not electrically conductive (in my tests... if people in other parts of the country would test theirs? it would be interesting.)
The metal cans are a type of waveguide... more of a feedhorn design.. they would be awesome pointing at the focal of a dish. if you were to put a 45Deg cone around the opening you would further increase the gain of the can.
The best thing to do is modify a existing 2.4ghz feedhorn or antenna. you'll find them on Primestar dishes and KU band old sattelite dishes. they need a bit of tweaking (filing on the stub) but work best and the little aluminum concentrator on the old sattelite dish types ( the set of concentric rings around the feedhorn opening) will give another 2-3db not in gain but in selectivity and rejection of off axis signals. (better noise floor)
Do not look at laser with remaining good eye.
You might try this guy out - its mainly build for AO-40 work in the 2.4 ghz range - should work really well for you 802.11 distance freaks :).
http://www.n3iyr.com/
Second, people have done the Primestar dish thing before and report 22db gain with it, not 30-50.
Third, according to the ARRL antenna handbook, the 200" optical receiving antenna known as "Mt. Palomar" has 148db gain. Frankly, I don't think anyone's satellite dish compares to this (or could, at microwave frequencies)
Remember, 100db gain means 10 million watts of effective radiated power for every milliwatt of input power.
Antennas with over 30db of gain simply are not that common.
No such thing as a Yogi.....you mean yagi. The link you have on your post is talking about STACKED Yagi's. By stacked, I mean they take 2 or more yagis and mount them on a boom with the elements paralell to each other and then have a different wiring. A piece of coax comes from each antenna and meets to form one piece of coax that's fed back to the radio. This has a way of increasing your directional gain alot. This is why this config is used for EME work on 2 M woith a 100 wat all mode 2 M rig. It can also be used for satellites.
You may be takling about a log periodic antenna where all elements are the same length, but are connected much differently together.
The O'rielly article is pretty amatuerish for even an amatuer. He stated that a Yagi is hard to build. Yagis are not hard to build, you just have to know what your doing. I can build a yagi for 2m cheap with a good metal hanger. Yagi's for 2.4 GHz are different, but they are doable, even by an amatuer antenna maker. That ARRL antenna book he bought is a good book and it can teach him how to build an antenna that he likes.
If you are just looking at increasing the omni directional range of your 802.11 card, these antennas won't do you any good. They concentrate the signal in a certain direction. They could be used successfully in linking (bridging) parts of a community wide 802.11 network, but where there would be a concentration of people, you would want an omni directional antenna on the AP. a 5/8 wave antenna would be good, but maybe they should look at a full wavelength aerial. At the frequency, it should not be that long (consider that CB'ers use a full wave all of the time on their pick-ups and tractors....).
Gorkman
Here's an old article, where a fellow achieved 14km in testing (not just signal strength, but actual data flowing).
Also reports of 57km achieved by Lucent engineers, staying within FCC specs.
-me
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