[TowerTalk] Helically wound verticals
WA3GIN in Alex. City, VA
wa3gin at erols.com
Sun Jun 4 21:59:21 EDT 2006
Just depends on what you want...convenience and ease of installation or
#12 on a 10ft 2" pvc pipe over 15 12ft radials will work fine on 40m.
Perhaps 2 "S" unit down from a 1/2wave dipole at 60ft. NVIS 15ft above
ground on 40m is about 1"S" unit down from the 1/2 at 60ft but when the
short skip is in the NVIS will blow the 1/2 away for the during of the short
For FD is suspect ease of install and take down is more important than "S"
meter readings. You're going to hear the same stations... Using a near
field radial system, 15 10ft radials will reduce your earth loss
significantly and actually raise your angle of radiation so you'll actually
work more stations within 500-1000 miles than you think.
I run three antennas on 40 m 1/2 at 65ft, NVIS ( 8 half-waves in phase 5db
gain straight up), and 1/2 wave wire cage vertical over 48 1/4 radials. I
can work the same stations on any of the antennas. Some days the vertical
does better than the other two...other days the 1/2 is the big performer and
still other days the NVIS. Today the Vertical was heard better at 900 miles
but the 1/2 high dipole heard the same station better on my end - go figure,
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Kelly Taylor
Sent: Sunday, June 04, 2006 7:24 PM
To: ersmar at comcast.net; Tom Osborne; Towertalk
Subject: Re: [TowerTalk] Helically wound verticals
> 2. A short, loaded vertical will not be as efficient and effective as a
full-size 1/4WL radiator.
Jerry Sevick may wish to disagree...
Actually, he showed in the 1960s that short, loaded verticals are so close
in efficiency to full 1/4-wl verticals as to be imperceptible. He built a
six-foot 40-meter vertical that performed so closely to his full-size he
didn't think the full size was worth the effort. (And this was waaaay before
NEC modelling was even a gleam in a computer geek's eye.)
Of course, Sevick put his verticals over the classic 120-radial ground
Verticals can be very good antennas: they just need lots of ground screen,
or be oriented as vertical dipoles. Of course, the better a vertical gets,
the worse it gets for Field Day...
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