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+--- Thread: Helical-wound radials for vertical antenna (/thread-517.html)
Helical-wound radials for vertical antenna - VK4WDM - 20-02-2018
I am trying to fit a 4 band HF vertical into a very tight space. It is mounted on top of a 5m high pole. I was going to use 4 elevated radials but there is no room to fan them out. My thought is to helically wind them on to a pieces of PVC pipe attached to the base of the antenna. I think there are some commercially-built verticals that have similar radials (CP6?).
What say ye!
73
Wayne VK4WDM
RE: Helical-wound radials for vertical antenna - VK4ADC - 20-02-2018
Wayne
Expect narrow SWR bandwidth with helical radials : the Diamond CP6 does have them but have a look at the freq response width at http://www.diamondantenna.net/pdfdocs/CP6A.pdf
To homebrew, try this calculator with the same values for min and max former diameters for straight wall PVC tube (non-shrinking) - it will at least get you into the 'frequency ballpark' :
http://www.vk4adc.com/web/hf-projects/45-hf-antennas/117-hf-helical-whip-calc
Doug
RE: Helical-wound radials for vertical antenna - VK4WDM - 06-03-2018
(20-02-2018, 09:16 PM)VK4ADC Wrote: Wayne
Expect narrow SWR bandwidth with helical radials : the Diamond CP6 does have them but have a look at the freq response width at http://www.diamondantenna.net/pdfdocs/CP6A.pdf
To homebrew, try this calculator with the same values for min and max former diameters for straight wall PVC tube (non-shrinking) - it will at least get you into the 'frequency ballpark' :
http://www.vk4adc.com/web/hf-projects/45-hf-antennas/117-hf-helical-whip-calc
Doug
Hello Doug
The narrow frequency response won't really be a problem because the station is almost all CW and digimodes. Now that the wet weather has gone, at least for now, I will wind the radials and see what happens.
73
Wayne VK4WDM