Cantenna?

[dpslusser]

hey guys...what is this?

http://www.jefatech.com/product/USB...Kit_with_80211bg_Wireless_to_USB_Adapter.html

 

[mancow]

It's a directional waveguide type of antenna used for a wireless USB WiFi device.

I think that a helical antenna works much better and really isn't that much more difficult to build.

 

[WisconsinRailfan]

The guys at AmateurLogic.TV did a few episodes on the cantenna, they show how to build one, also test it's performance.

 

[ka3jjz]

LOL! I had a good laugh on this one. Talk about remembering old names - the CanTenna was a Heathkit item which was a huge - gallon paint can size, as I recall - dummy load useful for hams testing transmitters safely. 73 Mike

 

[KevinGC]

Ah Yes, I remember it now. I had a cantenna back in the 70's to go along with my HeathKit HW-101 amateur transceiver. 200W output as I remember. Used the Cantenna to test the rig and tune the finals, etc.
It was a big resistor inside a paint can basically, filled with mineral oil to help dissapate the heat.

 

[kb2vxa]

Nope, with the Heath Cantenna you had to supply your own oil. If you remember that one you know how to build one of your own, there were plenty of construction articles in ham magazines of the day. My soldering iron mourns the loss of it's job and is now only part time employed.

Footnote;
The wise drilled a small hole in the lid and pushed in a rubber plug. The last thing you want when one heats up and the air at the top expands is a minor explosion and oil all over the place.

 

[ecoterragaia]

old thread

Hey guys, I've been lurking these forums for about a month now but not posting because I'm completely new to this and don't have a whole lot to contribute. I just bought my first scanner (PSR-700) and I love it, but I immedietely became obsessed with ways to increase its range I built my first successful 'rabbit ears' tuneable half wave dipole a week ago and it works great!!

The main subject of my post results from the fact that I've been spending a lot of time online reading up on antenna theory, and learning a ton, and also realizing that I've only begun to scratch the surface. My mobile broadband connection is terrible (the only option here in the boonies). In looking for ways to increase my signal using these new tidbits of antenna theory knowledge, I started experimenting with the RG6 coax I had laying around.

I cut a 20oz soda bottle at the bottom and wrapped a random number of turns of coax along the outside (18 turns now that I count), taped it up with duct tape, and ran about 1.5 extra feet out from under the duct tape wrap. I put the USB cable through the neck of the bottle and attached the broadband card inside, then taped the USB cable so that the broadband card is centered inside the bottle. I separated the shield and conductor on one end of the coax that I left hanging out, and cut them to each to 1/4 wavelength for the 850 MHz frequency that the broadband card locks onto at my house (Verizon's channel 770).

I tried hooking the shield and conductor to an indoor UHF TV antenna I had laying around, but it didn't do anything for the 'RSSI'. By accident, I touched the exposed shielding and conductor together, and whoa!! The RSSI went from the normal -102 dbm to -80 dbm !! I twisted them together and can get anywhere from -90 dbm to -78 dbm, depending on the position of the exposed shield + conductor, with a consistent -7 db loss. All background noise seems to be canceled out.

I was thinking of trying to design a 'cantenna' for the twisted end of the exposed coax, but I wonder if I should try the trap design first by connecting the shield and and conductor on both ends of the coax? Would this turn the whole unit into an antenna? Or is the cantenna idea better?

Thanks for any advice.,