From:
Fred Hopengarten K1VR 781/259-0088
Six Willarch Road
Lincoln, MA 01773-5105
permanent e-mail address: fhopengarten@mba1972.hbs.edu
On Thu, 07 May 1998 07:01:20 +0000 Tom Rauch
<10eesfams2mi@mass1-pop.pmm.mci.net> writes:
>I suspect that verticals just don't work well when frequency is
>raised much above 80 meters. Anyone else have any thoughts on that??
K1VR: Dana Atchley, then W1HKK and later W1CF, who held the patent on the
four square (along with W1FC, formerly W1FRR), believed that the key was
not vertical vs. horizontal at 40 m, but rather the ground losses
inherent in a vertical phased array design vs. losses associated with
horizontal antennas. He felt that even on 80 meters, a 3 el. Yagi would
always beat a 4 square (and WA1EKV, now K1KW proved it). I believe that
the success of the 6Y4A expedition, with verticals, is a function of
driving ground losses down dramatically by putting the verticals along
the shore. Additional example proof: W1KM, whose 80 meter signals are
spectacular. If the tide comes in too high, his feedpoint is underwater!
A single ground plane appears to be a poor radiator on 20-10, when it is
not. It is just that there are so many Yagis. On 40 there are now a
lot of Yagis. On 80 there are fewer. On 160, there are none.
Putting it another way, if you have a signal on 160 which is DOWN 1 dB
from a half-wave dipole a half-wave high, you have a SPECTACULAR signal!
>The trees probably don't help either, but they don't seem to hurt 80.
>(The trees that used to surround my 80 vertical were all about 70 to
>100 feet tall. I would think that a bad height for 80 meters, yet
>they didn't seem to hurt the antenna performance at all)
>
>Has anyone ever seen actual properly measured and documented data on
>this?
K1VR: No. But theories related to seasonality, i.e. sap in the trees,
seem to fail the test of changing resonant frequency or feed point
resistance.
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