Hustler CG-144 is one example of this type of antenna, I also had one of these from a different mfgr as my first 2m base station antenna, which worked ok.
Searching for information or a description of how this antenna works, how to build one, or a model turned up nothing. The only real unknown is the phasing coil, after sleuthing around the internet for a bit I found this phasing coil from Improving the Super-J. This appears to be fairly close to the CG-144 measurements, and does the trick. There is nearly 180 degrees of phase shift from one end to the other, and with a 1/4 wave element under it, and 5/8 above it close to 50 ohm match.
EZNEC model - 2m-58ovr14-wave-GP.
Issues: Bandwidth is narrow in the model (~2 MHz < 1.5:1), maybe because of 12 AWG wire to keep it simple.
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| Antenna view |
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| Elevation plot 2 meters height above average ground |
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| How to create the coil with EZNEC Create Helix function |