olanin1
join:2004-03-19
Reading, PA
|  Make my own omni antenna from coper wire
Im looking for a good cheap omni antenna to connect to my WRT54G. I found this on ebay »cgi.ebay.com/ws/eBayISAPI.dll?Vi···14557330
It says with 24 inches of copper wire you can make a 7dBi omni antenna. Is that true? If I use 48 inches of copper wire can I make a 14dBi antenna? 96 inches for 28dBi? |
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grcore
GOP FAIL
join:2003-12-06
usa
edit:
August 19th, @04:53PM
| said by olanin1  :
It says with 24 inches of copper wire you can make a 7dBi omni antenna. Is that true? If I use 48 inches of copper wire can I make a 14dBi antenna? 96 inches for 28dBi?
Theoretically you can make a 7dbi antenna out of copper wire, but it is not going to stand on its own. And if any of your measurements are even slightly off, its not going to get 7dbi.
There are omni's that get a higher dbi, but the pattern is like a pancake, and are only for real special applications.
1) determine what you want to do.
2) then ask for reccomendations on antenna's.
I bought the cable/connector kit he sells, and for the price its ok. I made a waveguide that pulls in about 14dbi out of a section of 4" duct. I don't use it much, but it was a fun experiment. I also made some bi-circle and bi-quad style antennas. Just to see how they worked, and to learn.
For anything other than experimentation, commercially produced antenna's are the way to go. I have had good success with some of the panel antennas for shorter range stuff (a mile or two). For longer range links, get a parabolic dish.
G |
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G0AOZ
join:2004-08-15
U.K.
| reply to olanin1
The homebrew omni's certainly look interesting... As to whether or not they work as well as claimed, I've no idea. However, the basic principle looks ok.
I would add that accuracy in cutting and shaping the wire is very important at these frequencies, with a few millimetres out possibly resulting in poor performance. Not only does an antenna need to be resonant on the desired frequency, but it also needs to present the correct impedance to the transmitter.
I've just discovered that a commercially made 7dBi omni produces very erratic results with a WAP54G on the higher channels, but set to channel 1 the AP performed faultlessly. This tells me that either it has a very poor impedance match at the higher channels, or more likely the antenna is cut to resonate at the lower end of the 2.4GHz WiFi band. Possibly trimming a millimetre off the element might allow it to work on higher channels, but since it's now working ok I'm leaving well alone!
You would not double the dB gain of this antenna by doubling its length. Provided you carefully matched any additional sections above the original element, you could expect to gain a few extra dBs at best. However, although you would still maintain an omnidirectional radiation pattern, the more gain you squeezed out of it, the flatter would be the signal. In other words, you would lose signal radiation above and below the plane of the antenna, at the expense of concentrating it outwards at 90 degrees to the vertical.
ROGER. |
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olanin1
join:2004-03-19
Reading, PA
| reply to olanin1
I pretty much just want a stronger omni antenna then whats included from the factory. No directional direction, just better overall range in all ways in the house.
Im looking at the Linksys highgain antenna that just came out. Its 7dBi and about $50 on ebay. Do you think that might be the best route for me? How are they? |
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dellsweig
Extreme Aerobatics
Premium,MVM
join:2003-12-10
Campbell Hall, NY
 ·Time Warner VOIP
| said by olanin1 :
I pretty much just want a stronger omni antenna then whats included from the factory. No directional direction, just better overall range in all ways in the house.
Im looking at the Linksys highgain antenna that just came out. Its 7dBi and about $50 on ebay. Do you think that might be the best route for me? How are they?
I am using the Radio Shack 5.5Db antennas on my WRT54G with HyperWRT 1.3 set at 42Mw. Netstumber shows me a nice clean strong signal ANYwhere in my house. Cant ask for any more than that
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»aerobatix.webhop.net |
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grcore
GOP FAIL
join:2003-12-06
usa
| reply to olanin1
That same guy sells a dual 7di antenna kit for 28.99
I have not tried these antenna's myself, but was thinking about them.
»cgi.ebay.com/ws/eBayISAPI.dll?Vi···tc=photo |
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