What can I say? I like projects that involve PVC. That way, when I goof it up, it's not expensive to redo.
This antenna was created by John Portune, W6NBC, and it was featured by the ARRL in QST (their magazine) and on a webinar. You can also find it on John's webpage.
https://w6nbc.com/articles/20xx-QSTcopperhelixantenna.pdf
As John describes it, it's a combination (slightly) off-center fed dipole and (continuously loaded) loading coil. What intrigues me is that it's a dipole that's shorter than 1/4 wavelength. Of course, mine aren't - but a spartan model could be. And it's advertised to have 1.64dBi of gain. Not bad.
This antenna has been assembled so sit atop a 1" PVC mast. The thin white tube is a piece of PEX epoxied into two 3/4" PVC caps. This ensures the feed line is centered in the 1-1/4" PVC tube - and through the bottom half of the dipole. I didn't get it up before the snow came so it will have to wait another couple of months. I have tested it out using packet radio and the transmissions went through just fine.
This is essentially the same antenna but this one was built for a hidden transmitter hunt. Interesting to note was that painting the copper tape moved the resonant frequency 2 MHz from 147.5 MHz to 145.3 MHz. I have heard that painting an antenna doesn't change its characteristics much, but the 2 meter band is only 4 MHz wide. I guess the phrase "much" is fairly subjective.
All in, these were fun and simple to build. I still haven't decided if the next iteration will be for 440 MHz or 915 MHz. I'll probably need some thinner copper tape.
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