On Fri, 31 Jul 1998 14:27:35 -0400 "w8ji.tom" <w8ji.tom@MCIONE.com>
writes:
>When I compared a dipole at 160 feet to a 3/8 wl vertical with a GOOD
>ground system, the dipole NEVER beat the vertical at any time. Most
>contacts reported the vertical two S units or more above the
>dipole. The dipole was solidly better within the state of Georgia.
I had somewhat different results in Colorado which indicated high angles
after sunrise.
My antennas were a 1/4 wave GP with 20 elevated radials ranging from 2 to
4 feet above
ground and a dipole with apex at 145 feet. I say dipole (NOT
inverted-vee) since I had
the ends pulled out about 600 feet from the tower so that the ends of the
antenna were
around 100 feet high. On 160, this means that the antenna was under 1/4
wavelength
above ground giving maximum radiation straight up at 90 degrees. (At one
point I even
put a reflector under it 6 feet above ground to try to maximize the
upward radiation!)
During many, many tests with the VK gang (mostly on SSB such that I could
get quick
comparative reports at different times before and after my sunrise), here
is a summary
of what I observed:
1. Before sunrise (~1 hour to 10 minutes before), vertical was usually
stronger by 1-2 S units.
2. At sunrise (~10 minutes before to 5 minutes after), both antennas
were about equal.
3. After sunrise (~5 minutes to 40 minutes after), dipole was usually
stronger by 1-2 S units.
Another fact which causes me to believe the radiation angle was high was
that my
Beverages (low angle antennas) ceased being as effective as the dipole
after my sunrise
for Pacific DX stations.
Of course the dipole was also the stronger antennna for local (<500 mile)
contacts, but I
made many DX QSO's under unusual conditions with the dipole that would
not have been
possible with the vertical/Beverage combination. For example, after
sunrise to the Asia/
Pacific area (YB0ARA when he was in Jakarta, VK9XS on Christmas Island)
and sometimes
to Europe and Africa before Colorado sunset. I remember one QSO in
particular when I was
total darkness near 7Q7XX's sunrise. The East Coast obviously had a good
opening
but I could just barely tell he was there while listening on my Beverage.
The pileup died
down after his sunrise (around 0300 I recall) and I remembered to try
listening on the dipole.
He was weak but clear as a bell and I worked him on the first call for a
new one! I recall
later checking his exact sunrise time and our QSO was about 15 minutes
after his sunrise.
The bottom line to all of this is that a dipole or another good high
angle antenna does have
its place in your antenna arsenal, but think of it as a complement to a
good low angle
antenna which will be better 99% of the time. It's those 1% situations
that sometimes
make you glad to have a high angle system!
73, Bill W4ZV
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