THE
ONE ELEMENT V BEAM!
A PROJECT BY KB4XJ
A
ONE ELEMENT V BEAM FOR 15 METERS
"I refer to this as my ONE ELEMENT
BEAM, It's a horizontal Vee!"
IT OUTPERFORMED 2
ELEMENT BEAMS WE HAD ON 10 METERS AND 20 METERS IN LAST YEAR'S FIELD
DAY!
IT HAS GAIN IN A SINGLE
ELEMENT DESIGN! THE db GAIN, IF FIGURED BY THE BOOK,
IS 3db OVER A
DIPOLE!.".....DARRELL REF 1
In
log-periodic dipoles, it was found that forward tilt increased gain
by
a 3 to 4 db over a regular log dipole.
REF2 Horizontal V Antenna for 15
Meters
"The HORIZONTAL V
ANTENNA FOR 15 METERS"
This often leds to the question of what is a Beam
Antenna. In it smallest of states, the Horizontal Vee, must be one of the
least researched or understood antennas.
After stumbling on misleading data one would think the
antenna to be a dud, that efforts to make such a antenna would be a waste
of time.....
This is far from the
case.....read
on......DARRELL.
A ONE ELEMENT "BEAM" FOR 15
METERS
CONSTRUCTION DETAILS
In log-periodic dipoles it was found that forward tilt
increased gain by a 3 to 4 db over a regular log dipole.
Ref
2
A little history, 3 years
ago, I was using a rotatable dipole for 15 Meters and had good results but
wanted something better. This dipole was built with a DAK dipole mount and
used 36 inch extenders with 6 foot 10 7/8 inch fiberglass CB whip
antennas. This worked well, but I wanted something a little better. I
spent more time reading about antennas and got interested in the
Horizontal V antenna and found that the basic V starts at 1/4 wave with a
90 degree
angle.
Ref
1
Time to build and
test my acquired knowledge.
The center of the antenna started life as 2 mirror
mount CB antenna mounting
brackets,
Coax
connection and mount
< AND CONNECTION
COAX>
Shown in the picture above, the first piece was flat on both
sides of 90 degree angle and a second 5/8 inch hole was added an equal
distance on the other side.
The second mirror mount is heli-arced to
the first piece, with the top piece horizontal and the bottom piece
vertical with the pole mount going down. (See picture above) Welding was
done at a local welding shop for a $5 bill.
Now I use the insulated CB 3/8
by 24 antenna mounting kits. You can pick these up at Radio Shack but get
2 and get the ones with bolts and stay away
from the flimsy screws. The kits come with 2
bolts, 2 long nuts, and the plastic insulators. Use one kit per 5/8 hole
on top, going from back to front ( bolt, insulator, thru antenna bracket,
insulator, long nut). Also while at Radio Shack pickup a couple of heavy
duty terminal ends for the end of your coax. The coax is done in a pigtail
fashion and connected on the bolt side of the antenna insulator hole 3/8
dia with at least a #10 wire connector for your terminal
ends.
Extender
Elements
Extender Elements
My elements consist of two 6 foot 10 7/8 inch fiberglass
CB whip antennas with 38 inch extenders.(See picture above) and note that
the original dipole used 36 inch but do to the induction between the
elements, the resonant frequency raised to 21.350 MHZ. The 38
inch extenders lower the frequency to 21.250 with a l to 1 SWR. I operated
field day on 21.205 and only got chased off frequency twice and came back
and retook the frequency, minutes later.
Extender drawing above by John Butler,
Planet Productions Dallas,
Texas
The extenders were made from 1/2 inch EMT tubing. On
one end a 3/8 by 24 long nut is inserted leaving 1/16 inch exposed for
soldering. Soldering was done with a 5% silver solder. On the other end a
3/8 by 24 bolt, 1 1/2 inch long, with a 3/8 by 24 nut attached to leave
1/2 inch of threads exposed was inserted in the other end leaving 1/16 of
the nut exposed and the 1/2 inch of threads.
The nut is soldered on the
exposed 1/16 inch of nut, take care not to weld on the exposed 1/2 of
treads. Arrows in drawing indicate weld points. Two of these must be
made.
Final Assembly and Performance!
The final assembly starts at the
center antenna mount. (See Picture above)
Connect coax pigtail on bolt
side of antenna center insulators, connect treaded side extender to
center, connect whip to extender and repeat for the other side. (See
picture above)
The entire 15 Meter antenna weights around 6 pounds and
was used on a 20 foot tower with an 18 inch truck wheel for a base, no guy
wires were used and it withstood a 30 mile per hour wind when a
thunderstorm hit just after setup for field day 2001. It has performed
better then I could ever have imagined. I learned what it was like to be
in a pileup and have fun, we even worked DX and had 49 of 50 states in the
24 hour period! We had directivity, and rotating from NE to NW we lost the
DX, but started working the Western States. I figure the gain over a
vertical at around 6 db, and a walk around the Horizontal V with a field
strength meter, (see diagram below), was enough to tell me that this antenna will
perform. A fellow ham came by, Gordon Blauser, and I let Gordon walk
around with the field strength meter and he walked away amazed with
how good the antenna performed with 10 watts running to it. He got
one of the prototype centers and was vowing to try using 2 hamsticks
on his V.
I also
have to get Spencer Whitmire, W4ERC's report on how another prototype
center is being tested on 6 Meter with just a couple of stainless steal
whips cut down to around 52 inches that will work on the Magic Band. The
center antenna mount could be made with a 6 or 8 inch longpiece of
aluminum angle 2 inch by 2 inch and 1/4 inch thick. This should give
plenty of space for the mast clamp.
Nay sayers may say that the
aluminum mast affected the radiation pattern but it worked for the good of
the antenna.
Using
the 36 inch & 38 inch extenders together with the whips puts the
antenna on 17 Meters.
Previous experiments with a different length whip
on the 36 inch extenders enabled operation on 12 Meters.
I lost
this bit of research and suppose that with adjustable extenders, (which I
haven't designed yet), would do the trick of getting multi-band coverage,
but below 20 Meters the antenna would lose the ability of 1 man erection.
Remember this antenna is directive and is rotated when used in the field
and is done by the arm strong method, and if guyed, use guy wires on
a slip ring.
FOOTNOTES ADDED BY DARREL.....
KB4XJ
The dipole formula of 468/freq will work but, an
extra 2 inches must be added to the final result.The induction between the
elements changes the resonant frequency of the antenna, and with a dipole
cut for 21.250 Mhz (SWR 1:!) when folded into the V shape, the
induction of the elements moves the freqency UP to 21.350 Mhz (SWR 1:1).
The Basic principle of the V antenna, when dealing with the rf radiation
lobes are that the lobes in the bisector of the V tend to add and the
other lobes tend to cancel.
I'am President of the Local Ham Radio Club,
and the chairman of the upcoming Field Day 2002. My 20 Meter
operator has vowed revenge for the beating he got in last years Field Day
from the One Element Beam and has stated that he's going to give me a run
for the money and has bought a NEW antenna which will replace his 2
element butterfly beam.
I accepted his challenge and told him I would
be using my V and that I wanted his competition AND that I wasn't going to
roll over and give up just because he got a new antenna.
The
proto-type 6 Meter Horizontal V will be used by Spencer Whitmire W4ERC,
the Vice President of the local radio club, Spencer was on 10 Meters with
a 2 element beam and was converted to a believer when he saw the V in
operation in last year's field day.
Spencer will give 6 Meters a try
with the V.
Our callsign for Field Day 2002 was K4W (Kilo Four
Whiskey).
I became an EXTRA in 12-4-98. The
One Element Beam is the results of several years of work on various
antennas, I was really depressed with the results of tests on so called
big signal antennas and finally went back to the horizontal dipole with
good reports. I remembered from my beginning in ham radio about the
inverted V that I used on 75 Meters and how I could get into Hawaii.
I also remembered that an inverted V could be made directive by the leg
angle. This was the turning point which led to the ONE ELEMENT BEAM.
While reviewing the logs of last years field day, I found KH6, VE6, VE3,
VE4, VE5, KP4, VE7, NP2, DJ2, NP4, TZ6, GO6, VE1, VE9, XE1, RX3, DL6, EA4,
OH4, G4, G0, EA5, EA3, DL1, OH1, RA3, DJ2, F6, PA3, F5, F6, AND VE2. I
found these prefixs in the log book of the DX worked during field day,
with the Horizontal V.
Antenna shown broken
down for field day.
Notice truck wheel used for
base
Top view radiation pattern "Estimate"
with a field
strength meter yields a 2 to 1 ratio off the
front
THIS IS THE BEST
PERFORMING ANTENNA I HAVE EVER BUILT!
DON'T LET THE SIZE FOOL
YOU.
All that is required to use this
antenna is a willingness to give it a try and then look at the
results.
It then comes down to operator skill as to how many contacts
you can do per minute.
It truly is AMAZING! Darrell Koranda
KB4XJ
E-Mail address kb4xj@strato.net
Reference1 The ARRL Antenna Book 1994, page
13-2
(chart gain of single long wire over a dipole\O-db ), page
13-5
(2 long wires placed in Horizontal V, give a 3 db gain over chart
on page 13-2)
Reference
2 The ARRL Antenna Book 1994, page 10-20
(forward tilt
of elements, gain increase of 4 db) log-periodic V array as compared to
log-dipole
20 THRU 6 METER VERSION
BY
LA0HV OF
NORWAY
CLICK
HERE!
Editors note: Please
give credit to KB4XJ for this
fantastic project!
"Many thanks to Darrell for all his efforts, hard
work and DEDICATION TO HAM RADIO
while getting this great project up
and running for all hams to enjoy!"
N4UJW
HAMUNIVERSE.COM
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