A=Benz-O-Matic propane torch; B=Lead-Free solder; C=Tape
measure: D=Tubing cutter; E=Sharpie marking pen; F=Solder
Paste; G=1/2 inch copper caps; H=Hardcopy of the above
drawing; I=Wet Towel; J=PreCut, ready to assemble parts of
the 2 meter J-Pole.
HAM
Radio and Commercial 2-way radio antennas
BUX COMM, 142 to 150 MHz; Fiberglass J pol
For low terrestrial
noise, use fiberglass elements. For optimum performance and gain,
feed with
BUX COMM "VBALUN."
Courtesy HRC Antenna
Newsletter (c)
BUX COMM, 435 to 450 MHz; Fiberglass J pol
For low terrestrial
noise, use fiberglass elements. For optimum performance and gain,
feed with
BUX COMM "VBALUN."
Courtesy HRC Antenna
Newsletter (c)
Two & Six Meter Beam Construction
Four element, two meter beam, elements can be tubular
aluminum, solid aluminum,
or for low terrestrial noise, use fiberglass
elements. This beam may be installed vertical, or horizontal.
For
optimum performance and gain, feed with BUX COMM
"VBALUN."
Courtesy HRC Antenna Newsletter
(c)
Four element, six meter beam, elements can be
tubular aluminum, solid aluminum,
or for less terrestrial noise, use
fiberglass elements. This beam may be installed vertical, or
horizontal.
Courtesy HRC Antenna Newsletter
(c)
Cubicle Quad Antenna Construction
Design-A-Quad Antenna
Calculate the total wire length for each element of a quad
antenna.
REFLECTOR = 1030 / F (MHz)
DRIVEN = 1005
/ F (MHz)
DIRECTOR 1 = 975 / F (MHz)
DIRECTOR 2 = 960 / F
(MHz)
between:
1) Reflector &
Driven Element = 730 / F (MHz)
2) Driven Element & 1st Director=
600 / F (MHz)
3) 1st Director & 2nd Director = 600 / F
(MHz)
Enter the
formula for the antenna calculation
Divided by Freq MHz
Total wire-length in feet is
FEET.
Total wire-length in inches is INCHES.
One of four sides in FEET = <- Use ONLY this number for "element spacing" when
entering the numbers (constants; 730 or 600)
above!
Total all spacing measurements (in inches) then add 2
inches for each end.
THE QUAD SHOWN BELOW IS AN EXAMPLE OF A QUAD DESIGN
USING DESIGN-A-QUAD ABOVE
The number "1" HAM station, field-day, and contesting, wire type antenna in
the world today.
The Windom is an antenna that enables operation, 80 through 2 meters, without
an antenna tuner.
By G. E. "Buck"
Rogers Sr; (60+ years as K4ABT)
VHF was fun, but most of
our enjoyment was on HF; September 1949, I was exhausted from climbing
poles and trees to move, remove, add, or change my single-band HF antenna's.
The trick
of it all, was to remember and change the plug-in "tank-coil" to match the
antenna band. My ole 807 rig was a home-brew, that I had built on an old
Atwater-Kent radio chassis. I had wound the tank-coils on phenolic,
plug-in coil forms (No, it was NOT a pi-section, tank-circuit, it was a real,
sure enough, link coupled output, no less).
I won't
forget the day and all the jumping up and down by some SWLs who were listening
on another band. I had my 80 meter (3735 kc, now called kHz) crystal
plugged into my homebrew rig, with the antenna connected and away I went to
make some serious early morning CW contacts on 80 meters.
CAVEATE:
The night before, I had been operating 40 meters. This morning, I
wanted to make some 80 meter contacts.... BUT, and However, I forgot to change
the "plug-in" tank coil from the 40 meter plug-in, to the 80 meter coil.
By
forgetting to change the 40 meter plug-in coil to the 80 meter coil, I had
doubled in the final.... and the 3735 rock, had put my RF signal output on
7470 kHz.
YES! you
bet I got a letter... matter-of-fact, I received a "Show-Cause" notice from
the FCC monitoring station at Powder Springs, Georgia, and furthermore, I
received a letter from an OO in Delaware. Never again, did I forget to
switch the plug-in tank coil when I changed bands... moreover, I made sure the
crystal I was using was for the band I was operating on. To help me
remember, I made an entry into my log book of each band change, and a
check-mark to indicate that I had indeed changed the tank-coil to correspond
with the crystal frequency.
Atenna
tuners were few and far between. This being the case, it's a good thing
the more up-to-date transmitter's used Pi-Section output tuning. Yes, I wrote,
"transmitter's;" Transceivers were unheard of in those days..... In
those younger years of my HAM radio hobby, I had used single band dipoles and
doublets for almost every HF Amateur band. I had tried long-wires, doublets,
dipoles, and Zepps, but again, operation was restricted to single band
operation, maybe two bands at most.
Enter; THE
WINDOM: Call it what you like, OCF, OCFD, or the name for which it is
named... its namesake is Windom. The Windom was, is, and will be the
number one antenna in the world for many years to come. The Windom was
first designed in 1923. It was fed by a single wire (coaxial cable was
not around in those days), The designer William Litell Everitt (his
photo is shown elsewhere on this page), brought it to the world in 1923, and
later wrote a brief about it in 1926.
A
detailed article by Loren G Windom, W8GZ written in the September,
1929 issue of QST Magazine. The Windom gained it fame then and
many times through the following years. I had heard of the
"Windom" and read a few articles about the Windom, but most of my thoughts
were ... ho-hum.. just another off center fed (OCF) dipole fed a bit
off-center.
Then
one fall evening in 1949, at a meeting of the GARC in the old "Sea Scouts"
club house near the Coosa River in Gadsden, Alabama; I listened as
some of my "Elmer's" discussed the Windom all-band HF antenna.
It was when Jack Kennamer, (W4YPC) (SK), mentioned using one (Windom)
antenna on all HF bands.... without an antenna tuner...! my ears went
directional !
That
last phrase caught my undivided attention. "all HF bands, ..etc" What ! A
multi-band HF antenna? Surely I had been blessed.
To
think that I could hang a Windom, and no longer have to climb the poles and
trees to hang another (single band) HF antenna was great news to me. To be
able to use it without an antenna tuner was icing-on-the-cake. For a
kid without extra funds, an antenna tuner was a luxury that I could not
afford. Even my transmitter was a single 807 rig I homebrewed on an old
Atwater-Kent radio chassis, my grand-father had given me.
In
those days (1945-1949), a BALUN was unheard of. My Elmer's described,
a means of connecting the coax to the off-center fed antenna using a lossy,
nine (9) turn coil of the coax feed-line at the feed point. This coil of
feedline coax formed a "de-coupling" loop. The de-coupling loop provided a
crude means of matching the feed coax to the antenna, and at the same time,
it would reduce the "re-radiation" (RF currents) along the outside (shield)
of the feeder coax. Later I began to study something called a "BALUN."
In
1958 I read more papers by Gillette Guanella which referenced a “current”
type
BALUN. then I came across Thomas O’Meara’s papers, “Analysis and
Synthesis with the ‘Complete’ Equivalent Circuit for the Wide-Band
Transformer.” This is when I made some changes to the design of the Windom
antenna. In 1970, I met Lew McCoy W1ICP (SK). We talked about
the Windom antenna and how we were building them. Lew had some ideas
that we felt had merit enough to give them a try… walla, almost like magic,
Lew's current type
BALUN design gave us the bandwidth that we needed to make the WINDOM
into an eight (8) band plus antenna (even adding some VHF bands).
FOR
THE RECORD: We have heard that some of our competitors are spreading false
notions about our BALUNS and antennas: For the record; Our
BUXCOMM Windoms have specially designed "Broad-Band Baluns" using
multiple cores and Teflontm covered, silver-flashed copper
wire. These
BALUNs enable operation from 1.5 mHz, well into the VHF region. Internal
BALUN connections are made using silver-bearing solder. Except the
special request
BALUNs (with eyebolt terminals), all
BUXCOMM BALUN's have large, right-angle, side screw termionals made of
Brass. The purpose of the right-angle, side-screw antenna connect
points is to enable antenna feed points connections without turning the
terminal connector. Another purpose of the bronze bearing Brass stud
is to enable the user to solder directly to the ring-terminal screw or to
the stud itself.
It
does not matter whose
BALUN you use; PLEASE, Please seal all terminals and appendages in or
out of the
BALUN with Coax-Seal CS 104. It does not matter whose
BALUN you use, NO ONE makes a
BALUN that is impervious to driving Rain.... sooner or later, it will
fail because of moisture ingress. If you don't wish to seal all the3
BALUN terminals, then drill a 1/8 inch "weep" hole in the bottom of the
BALUN.
UP
CLOSE, dealing with the reality of ground influence: Pay close attention to
what I'm about to say.
l
Impedance at the feed point of the Windom (or any wire type antenna)
decreases at resonance as the height above ground decreases !
or to
say it vice-versa.... and still have the same meaning or result:
l
Impedance at the feed point of the Windom (or any wire type antenna)
increases at resonance as the height above ground increases !
Having made this statement, I should clarify how we arrived at this axiom.
Here
in the BUXCOMM lab and our antenna farm, we made many tests with the Windom
at various heights above ground. After many, and I mean "many" trials
with the Windom at various heights above terra-firma, we found optimum
performance at thirty-three (33') feet above ground while using a 4:1 BALUN
at the feed point.
When
we raised the BUXCOMM Windom above 35 feet (raised to 55') we found the
feed-point impedance at 75 meters rose to 266 ohms. To make our Windom
appear at a more constant impedance, at the same operating frequency, we
made a change in the BALUN ratio from 4:1, to 5:1. With our 5:1 BALUN
(model B15KC51), the impedance at resonance remained fairly stable when our
Windom is 50+ feet above ground. When in doubt, use the following
rule-of-thumb to match/balance your Windom and BALUN;
Antenna height above ground:
BucK4ABT
*
No test results available above 70 feet
Today we have toroid cores and BALUN devices that
provide a more efficient means of coupling RF energy to the antenna
(reducing the VSWR, "standing-waves"), while performing better impedance
matching. In the drawing shown above, I've drawn the exact dimensions of the
Windom I built in 1949. The only differences in my Windom of 1949 and today
are:
1)
the material the insulators are made of, and 2) I've substituted a 4
to 1 BALUN for the (lossy) 9 turn, 8 inch diameter, decoupling loop.
As I
soon learned, this is one of the best and least expensive HF multi-band
antennas ever made. It appears as an off-centre-fed (OCF) dipole. This
off-center fed design is actually the way the first Windom antennas were
designed. The short side of this story is: the early Windom's
were fed with a single wire (non-coaxial) which allowed the RF to radiated
freely inside and outside the HAM shack.
UPDATING THE "ORIGINAL"
WINDOM:
Using
an open-wire feeder from the transmitter to the antenna was somewhat
dangerous when running power levels above 50 watts. This is in difference to
today's rules regarding RF radiation exposure, so to prevent this radiation
by the feeder wire, we have adopted the use of coaxial cable to feed the
Windom antenna. In order to do so, we had to move a bit further away from
center than the designer of the Windom had.
Instead of using a 330 ohm feed point on the Windom (approximately 14%
offset from center of the antenna and with the Windom more than 55 feet
above ground), we found a more suitable feed point that was closer to 33
percent off-center. This point comes closer to being a 233 ohm feed-point,
and since we adapted the Windom for coax feed, we now use a 1 to 4 (B15C41)
current BALUN when our Windom is 25 to 35 feet above ground, and a 1 to 5
(B15C51) current BALUN when our Windom is 40 to 55 feet above ground.
With
the offset at one third (1/3) distance from one end, we find the Windom has
a median impedance of approximately 223 ohms. This impedance is more
practical for using a 4:1 BALUN at the feed-point. In order to use a
6:1 BALUN and achieve a close impedance match, we must move the feed-point
further away from ground.
With
the use of our
Windom antenna, many customers will order the
6:1 BALUN because a friend told them to do so. These are customers who
are sometimes misled by the unknowing. The 6 to 1 BALUN is OK when employed
with the Windom feed point above or more than 55 feet above ground.
HOWEVER, we no longer use that 14 percent center offset. We have moved
to a more desirable feed-point (33 %) offset, and use a 4:1 BALUN (20 to 40
ft above ground or a
5:1 BALUN when we have the Windom feed-point 40 to 55 feet above ground.
When in doubt, use the
4 to 1 BALUN. In either case, the 4 to 1 and 5 to 1 BALUN's are
more efficient than a 6:1 BALUN.
Using
a 4:1 or 5:1 BALUN at the feed-point of the Windom antenna, we can operate
without the use of an antenna tuner. The Windom is an uncomplicated, easy to
use, harmonic related antenna. If we are the owner of an antenna tuner then
by all means use it. Since I run 200 watts (or less) I for one don't
like the idea of placing too many obstacles in line with my antenna, because
each transition from one feed-line, tuner, or other transmission line
transformer simply adds more losses into the equation and thus reduces this
wonderful antenna's high performance.
It could be that many young hams ignore the
multi-band Windom antenna because of its sheer simplicity and may think it's
too good to be true. Think about it, and while you are doing so,
remember, the more trinkets, and unnecessary inserts that are placed into
the RF path to the antenna are simply "window-dressing" or gimmicks.
These added "gimmicks" become an obstacle or loss to that extra bit of RF
signal that could have made that rare and needed contact in a contest
pile-up. The original coax cable fed Windom has proven itself over and
over, to be the number one wire type antenna with the most versatile and
valued performance record in the HF communications world.
Today, many radio amateurs
are using multiband Windom antennas with more than satisfactory results. It
would not be without reason that Windom antennas are being employed during
IARU HF World Championships! and most of all, by "high-stake-contests." The
complexity of feeding other dipoles and doublets, the losses in dipoles with
traps, and the esoteric marketing of some other antennas seem to appeal to
them more.
Remember
the axiom:
"When you have achieved perfection, anything more becomes a point
of diminishing returns." Enough said!
Trust
me on the above paragraph, as I have experimented with every Windom and
Jpole concept or design that can be imagined. Having built and sold
thousands of these two antennas, I've found that It's difficult to improve
on perfection.
80 through 2 meter WINDOMs
are complete and factory assembled and tested.↓
|
Similar to WINDOMs shown above, These WINDOMs are completely assembled,
ready to connect the coax, and erect. BUXCOMM Windoms are power rated at
1000 watts SSB and include all insulators, high-tensile strength, super
flexible PVC covering, Power-Flex, tinned, copper wire, connectors, and
BALUN. Our High-power versions are rated at 2000 watts and are
identified with an "HP" in the model number. See coaxial cable and
related items below. You can be on the air in no time, with any of our
Windoms.
BUXCOMM Windoms are the choice of Hams, World Wide
|
|
Figure D
The Windom can be installed as a Droop-End (see figure D below) or as a
sloper, but in no case, should the angle be greater than 90 degrees
against itself. To use an angle that folds against the pattern of the
opposite end, or the feed line of the Windom, could change the impedance
of the feed-point, change the multi-band features, and most important,
destroy the radiation characteristics of the antenna. |
A touch
of Class, The Windom and the J-POLE
By Glynn E. "Buck" Rogers Sr (70+ years as K4ABT)
The
J-POLE has been around since the early days of HAM Radio, and is a direct
descendant of the "Windom" Like the Windom or ZEPP, the J-POLE is a
spin-off, or a modified WINDOM for VHF and UHF. One of the first articles I
wrote about the J-Pole was in HRC magazine in 1958. Since 1958, I've written
several j-pole articles in other HAM Radio publications. Here, my
references are to the early, 1923 (version) Windom (Article by Loren G.
Windom September 1929, QST magazine) .
If you look at the feed method for the early Windom, it was fed with a
single wire. You soon see the similarity between the Windom, ZEPP, and
the J-Pole.
Look close at the configuration of the Jpole and the Windom, and you will
understand why in many of my articles in CQ Magazine and other publications,
that I often refer to the Jpole as a Windom, with the short section folded
back on itself to form the parasitic element. It is for this reason that I
feel these are two of the best antennas ever designed. Having said
this, you will also note that the Windom (and the Jpole) are powerful
antennas that provide outstanding performance on all bands above the band
for which they are cut or designed for.
The reason these two antennas perform so well (as Multi-Band antennas;
Windom for HF & lo VHF, Jpole VHF & UHF), is because they operate at
harmonics of the fundamental or lowest frequency for which they are
cut/designed. To add additional feeders
(ladder-line), other than 50 ohm coax or UNUNs is a waste of RF
energy. Only 50 ohm coaxial cable and a BALUN at the feed-point is all that
is necessary. Anything more, add losses into the equation that cannot be
overcome after-the-fact. See "frequency vs wavelength" and "ham-band,
harmonic relationships" in the following color-coded chart.
From: Richard Soikkeli
Sent: Monday, May 19, 2008 11:35 AM
To: [email protected]
Subject: Thanks for your fantastic Windom antenna!
Dear Buck,
Thank you so much for your patient technical help and the Buxcomm
Quality windom antenna. 2 weeks ago down came the 102' G5RV
and up went the
802136 BUXCOMM Windom.
Now I am filling the log book with countries I rarely could even hear
before, much less work, even with 500w CW. I have "busted" some
pile ups with a first or second call and got real 599 rpts from DX over
8000 miles away. The low noise factor and gain does the
trick. Also, I don't have RF into my son's computer speakers any
more and I'm sure the neighbors are happier.
I am advising our Field Day team to ditch the g5rv's as they don't
compare at all as you told me would be the case.
I only wish I had heard about BUXCOMM
Windom's sooner and had more fun working DX over the years.
I just installed a 2nd windom for my jr. high ham station. Now its
time to break out the QRP rig and see what it will do too. I will
be ordering more parts soon.
73 and thanks again, Rick
AE6RS |
To manage both CW and Phone portions of the HF bands with the Windom, some
"pruning" of the elements L1 & L2 can be made. Pruning (reducing) the length
of L1 & L2 may cause an increase in VSWR at the lower ends of the band(s).
Always remember to make the cuts proportional to each element. If you remove
12 inches (1 ft) from L1, remove only six (6) inches from L2.... If you
remove 2 feet from L1, remove one (1) foot from L2. Do not remove more than
3 feet total (L1=2 ft, L2=1 ft)
The Windom above is cut for the CW portions of the HF bands.
For the technical minded Windom builder, we opt for the
4:1 BALUN because it is; more efficient, and weighs less. Another nice
feature we found using our Rhode & Swartz Antenna Systems Analyzer, the
Windom exhibits similar feed-point impedance across the bands from 75
through 6 meters.
A word to the wise.... NEVER make any angle of the Windom (or any flat-top
antenna) more than 90 degrees. Ends can hang down, from a horizontal plane,
but do not allow the angle to be tighter than 90 degrees e.g. 75, 45,
degrees etc. A Windom may also be installed as an Inverted Vee, as long as
the Apex (Point where BALUN feeds the Windom) is not sharper than 90
degrees. The Windom is suitable for mounting as an inverted V, supported
between two masts, tower, or trees. The Windom wire elements must not come
in contact with limbs, vegetation or metal objects. In practice, try
to keep both ends (wire elements) of the Windom three (3) or more feet away
from any limbs, vegetation or metal objects.
The
BUXCOMM Windom can be purchased in several different band or lengths.
The number of bands covered is determined by the length.
The 160 thru 6 meters version is approximately 260 total length.
BUXCOM P/N 166260 With Current BALUN attached The 75 thru 2 meters
version is approximately 130 ft total length.
BUXCOM P/N 752130 With Current BALUN attached The 80 thru 6 meters
version is approximately 137 ft total length.
BUXCOM P/N 802136 With Current BALUN attached The 40 thru 6 meters
version is approximately 66 ft total length.
BUXCOM P/N 40670 With Current BALUN attached The 20 thru 6 meters
version is approximately 37 feet, total length.
BUXCOM P/N 20634 With Current BALUN attached
AN UPDATE:
Since writing this article several decades ago for a major HAM radio
magazine, I've received tons of mail (and eMail) asking for more
information, especially with regards to my 160 meter version;
The
BUXCOMM model 166260 Windom antenna is a horizontal wire, multi-band antenna
intended for use without an antenna tuner on 160, 80, 40, 30, 24, 20, 17,
15, 10, 6, abd 2 meters. The WARC bands of 30, 17, 15, and 12 meters by
using an antenna tuner. The antenna wire is made of 61 strands of silver
flashed wire and covered with non-metallic, super-flexible PVC insulation.
Each end of the BUXCOM Windom’s have end insulators made of high tensile
strength TyNYTE. The Center insulator is also Tynyte, and is fed by
customer’s choice of either a
4:1 or 6:1 BUXCOMM MasterMatch BALUN transmission line transformers. The
BALUN feed is attached near the one-third offset point according to the
feed-point required by the BALUN ratio (200 ohms/4:1, 250 ohms/5:1,or 300
ohms/6:1). By using a different feed-point for 4:1 BALUNS, a slight increase
in antenna efficiency is realized when using the B15C51 (243 ohm) feed which
results good VSWR on all referenced HAM bands. The antenna is suitable for
mounting as a dipole, supported between two masts, tower, or trees.
The Windom wire elements should not come into contact with any limbs or
other vegetation. Here's why;
The sky-blue insulation on the wire elements of our Windom antennas provide
esthetic blending with surroundings, added tensile strength, and most
important, it prevents oxidation of the wire. Oxidation can wreak havoc
after a few years exposure to the elements.
A few new HAMS do not understand why we advise against allowing the wire
elements (although insulated) to come in contact with metal objects, tree
limbs, and similar vegetation. Here, insulation does not prevent "proximity
influence (added capacitance), and RF absorption" by nearby vegetation, be
it limbs, or metallic objects. The same thing happens when the "sap" is up
in the limbs, as happens when the antenna elements come in contact with, or
near metal objects; stray capacitance, both inductive and capacitive will
surely detune a well engineered antenna
The
BUXCOMM Windom’s may also be mounted as an "inverted Vee". Do not exceed
90 degrees when erecting as an "inverted Vee". Specifications: Frequency
range: 1.8 – 2.0 MHz 3.5 – 4.0 MHz 6.8 – 7.4 MHz 13.9 – 14.7 MHz 27.8 – 29.8
MHz 49.5 – 54.0 MHz Feed-point Impedance 50 ohms VSWR <2.0:1 Horizontal
Polarization (If suspended as an Inverted Vee, do not exceed 90 degrees)
Maximum power 1200 Watts SSB, 750 W AM/CW, Wire Length
model 166260 = 260ft. WARC bands of 30, 17, 15, and 12 meters by using
an antenna tuner. Now-a-days, I see a lot of knock-offs of the windom, they
even try to change the name or use acronyms and try and relate it to the
dipole. The Windom is still a Windom, regardless of what they call it.
As with the "apple." The apple is still an "apple" regardless of what other
name they try to give it!
Having said that: Here then is "the rest of the story."
First of all, we'll address the formula, and how to determine the length(s)
of each section, using the same old formula that I used in 1949.
Long side.... = 468, divided by the frequency, then multiply by .64 (=
Feet)
Short side.... = 468, divided by the frequency, then multiply by .36 (=
Feet)
The
"Windom Antenna" was described by Loren G. Windom in QST magazine, September
1929. Pages 19 through 22. It is named after its inventor/designer.
Loren Windom, W8GZ, was first to reveal the antenna to the radio amateur
community by describing the antenna in the September 1929 issue of QST.
Although it was first build and tested by William Everitt (see photo), it
was by Windom's name that the antenna became known.
The Windom antenna is an off-center fed dipole with an unbalanced coax
feedline. In 1937, the Windom was first described as a compromise multiband
antenna. The antenna can be employed on 80, 40, 20 and 10m with
considerable, though acceptable levels of VSWR. What became perhaps the most
popular multiband Windom design of all, was the German-made Fritzel FD4
antenna, described by the late Dr. Fritz Spillner1, DJ2KY, in 1971. It had
the same dimensions as the multiband Windom antenna, but fitted with a 200 Ω
to 50 ohm, (4:1) balun in its feedpoint and fed with coax.
In recent years, some operator's are using 300 to 50 ohm, or 6:1 baluns.
They base their decision on the simple math that the feed point is three (3)
ohms closer to 300, than 200, simply because the feed-point of the Windom is
243 ohms nominal. Has anyone ever heard of "surge-impedance?" In tests,
we've found, there's no significant difference in performance either way.
Therefore, the trade-off is a matter of personal choice. Mine of course, is
the Windom with a 4:1 Current BALUN (B15C41 or B15C41XV). If you plan to run
more than 1000 watts SSB into our Windom, we suggest you request our Windom
with the B15C41XV Current BALUN rated at 1.5kW SSB.
Here are some final notes:
In our
BUXCOMM BALUN's, we make it a point to polarize the posts of our
MasterMatch series, identified by a RED or BLACK dot, or ring on the brass
terminal posts. This provides the user with a benchmark that allows the
BLACK post to be used towards the "cold" side of the antenna and the RED
post is connected to the long, or "hot" side of the antenna. Some old-timers
of my vintage, refer to the cold side of the antenna as the "parasitic"
element.
As a point of interest, in some installations, the coax feed-line may pass
through the RF field of the antenna, RF current can be introduced into the
feed-line after the balun. In this situation, a 1:1 Current Choke should be
inserted into the feedline near the feed-point of the antenna.
A few notes about "SkyWires" or, the full-wave Loop Antenna
Loop antennas have a fairly low impedance when they are built one (1)
wavelength in circumference. The low feedpoint impedance at harmonic
multiples of the resonant frequency as opposed to dipole antennas, have low
feed-point impedances at ODD multiples of the resonant frequency.
When a
Full-Wave Loop
is operated near resonance on the desired band, a 5 to 1 or 2 to 1 balun
works very well, when using 50-ohm coaxial cable to the radio from the balun,
VSWR at resonance will normally be below 2:1. An external antenna tuner is
not required. If necessary, the transceiver's internal antenna tuner
may be used.
Typical
SWR Plot of full-wave horizontal loop at approximately 40 feet above average
ground using BUXCOMM MM21, 2:1 balun should exhibit an VSWR at resonance
below 1.5:1.
Application Notes for BUXCOMM BALUN`s
Definitions: BALUN = Asymmetrical to Symmetrical; UNUN =
Asymmetrical to Asymmetrical
1:1
BALUN: 50 ohms to 50 ohms, or to feed dipoles and similar antennas with 40
to 75 ohm feed points.
BUXCOMM model MM11
1:2
BALUN: 50 to 100 ohms. This Balun is suitable for feeding Vertical Antennas,
Quads, Loop antennas and Ladder Line antennas.
BUXCOMM model MM12
1:4
BALUN: 50 to 200 ohms. This Balun is suitable for the coupling 50 ohm
coaxial cable to Windom’s, and off-center-fed antennas.
BUXCOMM model B15C41
1:5
BALUN: 50 to 250 ohms; Suitable for coupling 50 ohm coaxial cable to a
Windom’s, when the Windom is more than 50 above ground.
BUXCOMM model B15C51
1:6
BALUN: 50 to 300 ohms. This BALUN is suitable for the adjustment to
asymmetric fed dipoles such as Windom’s, G5RV, and zepp antennas. The BALUN
is fed directly to the Windom and similar antennas. With double-zepp and
G5RV antennas and use of asymmetrical feeder, the BALUN is positioned before
entry of the cable into a building.
BUXCOMM model B15C61
1:9
BALUN: 50 to 450 ohms for coupling Asymmetrical to Symmetrical feeders.
BUXCOMM model MM91
1:9 UNUN:
asymmetrical to asymmetrical (unbalanced to unbalanced) Long wire antennas,
Ground Plane`s, Verticals, and some types of "beverage" antennas,.. etc.
BUXCOMM model MM19LW
1:16
UNUN: Similar to above application; asymmetrical to asymmetrical (unbalanced
to unbalanced) Long wire antennas, Ground Plane`s, Verticals, and some types
of "beverage" antennas,.. etc
An
Improved G5RV Antenna:
The
original G5RV antenna was developed by Louis Varney G5RV for 20 meters.
Although his design was a good one, he used the 450 ohm ladder line as a
feed-line-to-antenna impedance match, and without the use of a BALUN. We
discovered that feeding the 450 ohm ladder-line directly with an antenna
tuner, left us with a shack full of RF…HOT mics, hum, and in some cases, we
had "squeals" from rectified RF getting into the microphone audio path,
within the transceiver, a sure sign of RF-Feedback (base rectification).
To make
the G5RV more "user-friendly" and with less RF exposure within the
HAM-shack, we added an MM11 BALUN at the lower end of the 450 ohm
ladder-line, and from the asymmetrical input of the MM11 BALUN (outside the
HAM shack), we used 50 ohm (low impedance) coax to reach the antenna tuner
inside the HAM shack. We’ve found that this improvement to the G5RV has put
more of our transmitted RF into the elements of the antenna, and made the
antenna virtually noise free and reduced re-radiation as much as 85 percent.
Without
using an external antenna tuner, we’ve found that our transceiver will work
into the 50 ohm coax and the MM11 BALUN with VSWR below 2:1 on the bands the
G5RV is cut for.
By
making the additional BALUN and coax improvement to the original 20 thru 10
meter G5RV, it is now possible to build the G5RV for more bands, and thus
cover lower bands and frequency’s. We now have a means by which we can have
an antenna that fits almost any real-estate configuration, from as little as
27 feet (8.2 m), (20 thru 10 meter bands) to 207 feet (64 m) (160 thru 10
meter bands).
BUXCOMM
now builds G5RV antennas in four (4) versions and lengths. Depending on your
available space, you may choose the size and version to fit your needs and
available real-estate space.
Model 80
thru 10 meter band coverage; Overall Length BALUN
G5RV-16010 160 to 10 meters 208 feet or 63 meters
G5RV-8010 80 to 10 meters 102 feet or 31 meters MMG5
G5RV-4010 40 to 10 meters 52.5 feet or 16 meters MMG5
G5RV2010 20 to 10 meters 26.5 feet or 8,1 meters MMG5
Here's more commendation for our BUXCOMM Windom antennas:
From: M33Access Sent: Monday, October 16, 2006 2:55 PM To: [email protected]
Subject: BUXCOMM WINDOM
Hello
I couldn't
resist the opportunity to tell you about your Windom antenna I bought a
couple weeks ago. I have been off the air for a number of years. Probably
close to 15 to be exact. My oldest son got his ham ticket this past summer
and started buggin me to get on the air. That's when I decided to bite the
bullet and get on.
After working
for days trying to make my old "Inverted V" work. I turned to you folks and
your off center fed Windom. Since then I hung the antenna at the 70' mark on
my tower and the long end to about the 55' mark on a tree in the back yard.
My station is simple, I use the Kenwood TS-180s barefoot to the Windom. I
love to work rtty and packet. I am using an ancient AEA Pakratt232.
I have heard DX
that I never heard in my years of being a licensed Ham. I have worked Italy,
England, South Africa and last night I worked a station in Chile. CHILE! Now
that is at the other end of the world! This is so neat, I can't tell you how
much I am loving your antenna. Remember this is barefoot. I have my dad's
SB-230 amp, but it's not hooked up. I don't have the DIN plug for my 180
yet.
If you have
customers asking how your BUX Comm Windom antenna works, give them my call
and I will be happy to meet them on the air.
73, and thanks
again.
Bob WB8UJB
From: Andy
KA3ODJ
Sent: Wednesday,
June 07, 2006 6:49 PM To: [email protected] Subject: 166261W100 Just
wanted to let you know that your 166261W100 antenna here at KA3ODJ is
working like Gang Busters. Purchased the antenna primarily as a 160 Meter
antenna for the Internet Remote Base. The SWR and performance exceeded what
I had expected, I have added it to the selection choices for the other
bands. Can not wait to get the ends up higher, they are only 35" or so right
now. Getting good reports from the users of the Internet Remote Base. No RF
Problems at the coax end either, I also am using one of your Master Match at
the antenna switch. I am running an Icom PW1 and in the past, I've had RFI
issues in the shack resetting the computer, but no more, with this new
BUXCOMM Windom, it's clean as a whistle. Feel free to give your antenna a
try if you like. To operate Remote, You will have to download W4MQs software
to get access. http://wpmq.com. Thanks for a great product at a fair price.
Andy KA3ODJ
Our Windom Measurements
|
Freq mHz |
1.9 |
3.5 |
7.1 |
10.7 |
14.2 |
21.4 |
28.5 |
|
SWR |
1.8 |
1.2 |
1.8 |
1.55 |
1.33 |
2.1 |
1.25 |
|
Impedance |
233 |
218 |
158 |
161 |
280 |
256 |
190 |
Metric Conversion
|
INCHES
To Millimeters Inches x 25.40 To Centimeters
Inches x 2.54 To Meters Inches x 0.0254 From Millimeters M x 0.03937
From Centimeters C x 0.3937 From Meters M x 39.3701
|
FEET
To Millimeters Feet x 304.8 To Centimeters Feet x
30.48 To Meters Feet x 0.3048 From Millimeters M x 0.00328 From
Centimeters C x 0.03281 From Meters M x 3.28084 From Centimeters C x
0.01094 From Meters M x 1.0936 |
YARDS
To Millimeters Yards x 914.4 To Centimeters Yards
x 91.44 To Meters Yards x .9144 From Millimeters M x 1.094 x 10- 3 From
Centimeters C x 0.01094 From Meters M x 1.0936 |
WINDOM, to ZEPP, to VHF J-POLE.
BUXCOMM BALUNS are more than just antenna matching devices:
* Help keep RF out of the shack.
* Provides maximum transfer of RF to the antenna.
* Elemination of radiation from the feeder cable
* Makes the antenna radiation pattern predictable.
* Reduces QRN and TVI to the neighbors.
BUXCOMM BALUNs
should be installed at the antenna feed point, or where the coax or
feed-line attaches to the above ground antenna. BUX BALUNs are used to
connect balanced antennas to unbalanced transmission lines, such as coax
cable. Their primary purpose is to prevent antenna (RF) currents from
flowing down the outside of the cable. Another function of the BUX BALUN41
is to match the impedance of an unbalanced coax to the balanced feed point
of a balanced input antenna(s). BUX Line-Isolator BALUNS may also be
installed anywhere along the cable to prevent the destructive influence of
induced RF currents (VSWR). The best location for the BUXCOMM LISO is
to install it at the output of the transceiver or between the linear and the
coax cable feed line to the BALUN at the antenna.
The illustrations,
drawings, and documentation shown on these pages are for use at the readers
discretion and is NOT a recommendation by BUXCOMM Corporation, its owners,
or employees.
Noise is the enemy of
Packet, Voice, Data, and Digital Communications. In addition to providing
Equipment and Personnel Protection
from lightning, a good ground system will reduce noise in your Packet
Station, or your mountain-top communications site.
G. E. "Buck"
Rogers Sr.
If you follow these Lightning Protection & Grounding procedures
ANTENNAS
AND SUPPORTING STRUCTURES
Metal antenna structures that are anchored into the
ground are inherently self-protected. Some radio systems antennas and
beams may be unlikely to be damaged by direct lightning strokes, but
they should be bonded to metal supporting structures to eliminate
arcing. If the ability of an antenna to withstand direct lightning
strokes is doubtful, Lightning rods atop the tower or supporting
structure, to intercept strokes should be provided where the
transmission pattern permits.
Lightning rods may be attached directly to a metallic supporting
structure and should protrude sufficiently above vulnerable elements to
provide an adequate "cone of protection". Top lighting fixtures may also
be subject to damage if they are not properly shielded. Metallic antenna
towers, either guyed or self-supporting, provide an excellent conducting
path for stroke currents but the footings, base, and guy anchors of such
structures must be properly connected to suitable grounding electrodes.
When wood poles are used to support antennas a lightning rod should be
provided at the top of the pole to intercept strokes. This lightning
rod should have a large size ground wire cadwelded to it and routed to a
good ground system. This will give protection against pole splitting and
possible antenna damage. In a common arrangement, a ground rod is
attached to the pole with one end protruding sufficiently above the top
of the pole to provide a suitable cone of protection. A #6 AWG (or
larger), solid, bare copper, down conductor is connected to the rod and
stapled directly to the pole on the side opposite the coax or
transmission line to the antenna. All pole-top hardware, the antenna,
and any supporting guys should be bonded to this grounding conductor.
At the base of the pole the shields of lines, equipment cabinets, and
any other conducting objects should be bonded to the down lead which
then must be connected to the common area ground system similar to that
shown below.
An overview of how a communications site is grounded.
Your site should not contain an independent ground(s).
ALL grounds should be connected together as shown in the illustration
above. A single point (common) ground is noted by the Master Ground
Bar or MGB, as shown. Ground rods are chemical rod systems that
are used in areas where grounds are hard to achieve.
The drawing above is a "cut-away" that illustrates how the chemical
"L" ground is installed. Chemical ground rods are also available in
straight or "vertical" shaft design.
NOTICE:
When working around electrical
earth or signal grounds, Never intrude, interfere with, or
interrupt, any part of this ground system. Above all, do not
"break" or open your electrical power ground. In no way should
you compromise your electrical service grounds! When in doubt,
call or consult your utility company and a licensed electrician.
Remember, lightning is unpredictable. A direct lightning
strike or a nearby hit/strike can damage your equipment. In
addition; It can cause injury to those near the strike, start
fires, or cause death. Again; When in doubt, call the local
utility company or consult a licensed electrical contractor or
specialist.
For those who want top level
lightning protection, here are a few of the current generation in
lightning protection devices.
A
Secondary
Lightning Protector
Remember the axiom; "An ounce of prevention is worth a pound of
cure." This lightning protector contains a modified spark gap
that provides that ounce of prevention. We offer this device as a
secondary radio protector. Remember, there is no substitute for
a good earth ground, AC line surge, and spike protection.
Keep all ground leads as short as
possible. Where lightning is involved, we make no warranties.
OrderLine Only; toll-free 1 866 300 1969 Monday > Friday 9:AM to
4:PM, eastern time
 |
7516 |
Remember the axiom; 'An
ounce of prevention is worth a pound of cure.' This
lightning protector contains a modified spark gap that provides
that ounce of prevention. . Remember, there is no substitute for
a good earth ground, AC line surge, and spike protection. Where
lightning is involved, we make no warranties. We offer the 7516
as a secondary lightning protector. Ground wire attached to wire
lug. |
FYI... No inline device will
protect against a powerful, direct lightning hit.
The industry "work-horse" is the model 3710 (and
3730) Ground Tester. I consider my model model 3730 to be
one of the most "user friendly" devices that I have ever used to test an
existing ground system at communications sites.
OrderLine Only; toll-free 1 866 300 1969 Monday > Friday 9:AM to 4:PM,
eastern time
|
Digital Ground Resistance Tester Model 4610
(When it comes to making ground measurements and soil resistance
tests, this "magic box" is my first choice!)
- Measures from 0 to 1999 ohm
- Direct reading bridge
- Fall-of-potential method
- Autoranging
- Measures Ground Resistance (3-point) and soil resistivity
(4-point)
- Step voltage tests
- Touch potential measurements
- Continuity tests on bonding
The model Digital Ground Tester Model 4610 performs accurate ground resistance
measurements (3-point) on single rods or computer grids, and soil resistivity
measurements (4-point). It may also be used for step voltage tests and touch
potential measurements.
The model Model 4610 is autoranging: It will automatically seek out the optimum
measurement range. To use the tester, simply connect the leads, press to
measure, and read. This rugged, easy-to-use tester is ideal for maintenance
crews performing multiple and repetitive tests.
|