A
Reflector Element underneath a Dipole
(Worth
the trouble?)
(8/4/00
I'd like to share my recent experience with installing a wire reflector element underneath my 40 meter dipole.
First of all, why put a reflector underneath your
dipole? Wouldn't that somehow distort your radiation pattern?
Wouldn't that increase the amount high angle of radiation, reduce the amount
of low angle radiation, therefore
reducing your chances of working DX on that antenna?
Well, for years now I've heard guys on 75 meter SSB talking about the reflector
element they had installed
underneath their 75 meter dipole. From what I remember of their conversations,
the main reason they did this
was to increase their signal out just a few hundred miles. Most of the guys I heard
talking about this were the
type of guys that spend most of their Amateur Radio hobby "hanging around" with
the same group on the same
frequency night after night running full power. Most of their group was within a few
hundred miles, so they
weren't concerned with their 75m signal being heard far away, they just wanted to increase
their effective
radiated power out to a couple of hundred miles or so, competing to be the "Big
Gun" of their group...
Six years ago, we lived on a small lot (50' X 90') in Virginia
Beach. While in Virginia Beach, I was bitten
by the QRP Bug. Running qrp was tough with the limited antenna space though. We were
lucky enough to
have some woods behind our property line so I "borrowed" a little airspace from
the woods and put up a
G5RV. The G5RV proved to be a great limited space antenna and I soon added a GAP
Vertical antenna
that also proved to be a great antenna for someone with a small backyard. During our
stay there I installed a
"Mini-Quad" that absolutely blew me away. The Mini-Quad was my first
Amateur Radio Experience using
a rotatable antenna. Keep in mind the Mini-Quad wasn't exactly a high dollar full
sized yagi, but it
was rotatable and exhibited some decent gain over the other antennas I was using. I
was hooked!! What a
difference in signal strength between the other antennas!!. It was then that I began
to long for a larger piece
of property to erect my own "antenna farm". About that time The U.S. Coast
Guard transferred me to
Washington, DC.
We ended up buying a home on a gorgeous 1 and 1/2 + acres lot in the woods
of Stafford County Virginia
about 45 minutes S/SW of Washington, DC. The lot was loaded with woods and trees and
has a ton of huge
(80ft +) Poplar trees. I quickly erected an antenna farm and now utilize the
following antennas:
+ 160 M Zepp
+ 80 M Coaxial Dipole
+ TriBander @ 35 Feet.
+ 13 ele 2 m yagi @ 40 Feet.
+ 5 Band Vertical ground mounted w/radials for 10-40 (not in use on 80m)
+ 40 M Dipole w/reflector (Wire Yagi/ "Cloud Burner?")
It was after buying this piece of property that my QRP bug began to grow
rapidly. More QRP rigs, more
coax, more wire, more antennas in the trees!.. I was constantly striving to improve my
antenna systems. I
erected slopers, dipoles, loops (horizontal and vertical), longwires, zepps and
delta loops.
Most of my serious QRP-CW work was being done on 40 meters, my band of choice
for low powered
CW operating. Operating 40 meter QRP-CW most of the time means that the majority of
my QSOs
ended up being within a few hundred miles from my home QTH. Soon I became bored with
the QSOs
at the 5 watt level and started "milliwatting"... This got the
"wheels-a-spinnin" in my head...... Hey, why
not put a reflector element about 21 feet below my 40 meter dipole and see what
happens?
Lowering the 40 meter dipole was not a problem and loosening the support
on each end of the dipole
only took a minute or so. In less than 3 minutes, the 40 meter dipole was
hanging down to a level where
I could touch the end insulators while standing on the ground. I measured a piece of
antenna wire (the
same type I used to originally build the dipole), that was 5% longer than the dipole
(radiating element),
Then I tied a 21 foot piece of support rope just outboard of each end insulator and
hoisted the antenna
back up until the end of each of the the 21 foot pieces of rope were about 6 feet off of
the ground.
Then I tied each end of the 21 foot pieces of rope to the end of the reflector element and
hoisted the
antenna back up into position. Easy as pie!!
When I got back in to the shack, WHAT A DIFFERENCE
IT MADE!!!. I was on 40 meter SSB
at 100watts (QRP is my first love, but I'm a "closet" QRO operator too...) and
continued a QSO I
was having with a group of about 7 guys there (I had told them I was going to install the
reflector
and be back in about 1/2 an hour). They were all waiting for me to return.... It was
about 1 in the
afternoon and the guys that were within 250 miles or less noticed a remarkable increase in
my signal
strength. The guys that were further away (one was in NW Ohio and one was in Western
Tenn),
said my signal had dropped. So there ya go!, proof in the puddin' that it works.....
You might be saying to yourself, hey!, the propagation might have
changed while he was putting up the
reflector element... Well, this particular day was one of those "golden" days on
40 meters. You know the
type of day I'm talking about. The kind of day where there is hardly any atmospheric
noise, QSB is
almost nil, and everyone's signal is booming in......... Just to "double
check" our test, I had the guys
stand by and I ran outside and furiously "undid" what I had just done (took down
the reflector) and
ran back inside...... As soon as I sat down and started talking, the close-in guys said my
signal dropped
off and the guys in Ohio and Tenn said my signal was back up......Once again I ran outside
and put
back up the reflector element and when I returned to the shack the results were the same
as when I
first installed the reflector less than 30 minutes earlier...
The antenna I call a 2 element wire yagi, or "Cloud Burner"
might not be for you, especially if you
are living on a small city lot. But if you are a lowband QRP enthusiast like
myself and enjoy close-in
"milliwatting" on 40 meters this antenna will do the trick....
72/73
Doug W4IDW