[Lowfer] FW: 600MRG> Helically wound vertical on a city lot>NO WAY!!!

[John Davis]

>Wouldn't there be a huge AC and DC resistance in all the wire??? That is
>what I was thinking. I believe that it takes close to 1/2 wavelength of
wire
>to wind a helical 1/4 wave vertical. That would be about 2811' of wire.

This is indeed a factor to bear in mind, Mike.

Of course, that assumes one really wants to attempt to make the thing
self-resonant in the first place.  The term "helical 1/4 wave vertical" is a
rather loose usage.  Self-resonance is pne property of quarter-wave
antennas, and that's about the _only_ property that is duplicated with a
helical.  Current distribution can be made to look more sinusoidal than with
a conventional vertical, but that's not always a good thing; a seriously
top-loaded conventional vertical can be made to have a greater effective
height than a "pure" helical.  Radiation resistance is not equivalent to a
real quarter-wave, by any means, and losses can be very high--in part, due
to the problem you just mentioned with all that wire.

I've been an eager experimenter with helicals in the past, and will probably
resume playing with them once I no longer have obligations to my job.  But
the objective will be to use partial helical windings as a tool to optimize
current distributions more than anything else, as my early MedFER
experiments quickly taught me that a "standard" half-wavelegth-of-wire
helical was no more effective than a well-made conventional antenna with
proper attention to loss management, and sometimes more of a pain to build.

73,
John