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We built this antenna using plans from http://www.wireless.org.au/~jhecker/helix/
Use a PigTail or a HomemadePigTail to connect to your WirelessCard
MattWestervelt, StephenBriggs, DanEgnor and KenCaruso showed up at the garage and built the second helical. Here are pictures. We expect a distance test to happen next week.
We are using left hand winding on this antenna to match the first helical.
Super Glue. Pretty strong stuff.
Gloves are a good idea when working with Super Glue.
Wrapping is a pain. you need two people. vice grips are a recommended item for this.
Wrap tightly to keep on track. remember. there is no world Super Glue shortage.
Nice eh?
What size wire did you use for the windings? 16 gauge
We could have used a pie tin like the first antenna, but decided to use galvanized tin instead.
On this antenna we decided not to go through the endcap / copper tape nightmare and glued directly to the reflector. We have not tested this yet. hopefully it will work.
To adjust for not having a bolted down endcap, we decided to use a lot of caulk.
Put the caulk in here.
Here is a shot of dan reminding us that caulk isn't funny.
The antenna is currently drying at the garage. shots of the finished and tested antenna should be up in a day or two.
10/12/2004 - Be very careful with your selection of PVC pipe. The Hecker design relies on thin wall material such as under-sink drain pipe. High pressure pipe (thick wall) is a poor choice as the velocity factor of the dielectric has a significant impact on overall tuning. Helixcalc and others assume open air or close to it. I placed a unit built with high pressure PVC and Hecker's dimensions on a HP 8720D network analyzer only to find it was optimized for some freq considerably lower than 2425 MHz. See
http://www.qsl.net/pa0hoo/helix_wifi/index_eng.htm
It would seem that he too used high pressure pipe and compensated for it using smaller dimensions. Only problem is the variables of using such materials are too great to reproduce reliably. I plan to create and test several models based on information derived from this link as well as attempt to achieve the spectacular results Hecker saw with his model using thin wall PVC. Reaults and pics will be posted at http://www.safe-pc.net/. [added nov 13, 2004 by pa0hoo: I used 4mm thick wall indeed, this is the common European wall thickness for drain pipes. BTW: the properties of the PVC itself seems to be less reliable.]
A true open air design that also intrigues me but looks like too much work is shown (translated to English courtesy of Google) at
10/03/2006
Results are in for the highly directional 2.45GHz helical Wi-Fi antenna project at http://www.safe-pc.net/ . This antenna can be used for long range point to point Wi-Fi networks, amateur radio satellite link and covert war driving. Check out the entire article at
http://safe-pc.net/helical.html
Cheers!
Here is a link to another helical design
http://www.havilandtelco.com/homepages/gregwycoff/TSLD012.HTM (Down?)
Here is a link to a Normal Mode Helix Antenna
http://www.freenetworks.org/index.cgi/NormalModeHelicalAntenna
And here a page on the same site with some general 2.4 Ghz stuff:
http://www.havilandtelco.com/homepages/gregwycoff/bill.htm (Down!)
Schedual 20 pvc pipe is the thin type and schedual 40 is standard home use schedual 80 is high presure.
