My Favorite Multi-Band Antenna

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, 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.

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 Windoms 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 600 ohm feed point on the Windom (approximately15% offset from center of the antenna), we found a more suitable feed point that was closer to 33 percent off-center.  This point comes closer to being a 240 to 270 ohm feed-point, and since we have adopted the Windom for coax feed, we must now use a 1 to 4 ratio BALUN to match the 50 ohm coaxial cable to the approximately 200 ohm antenna feed-point.

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 may be OK when employed with the original 15 percent offset feed point, HOWEVER, we no longer use that 15 percent center offset.  We have moved to a more desirable feed-point (33 %) offset, and used a BALUN with more efficiency than a 6:1 BALUN.

With the offset (feed-point) at one third (1/3) distance from one end, we have found the Windom has a median impedance of approximately 245 ohms.

Using a 4:1 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 build, harmonic related antenna.  If you are the owner of an antenna tuner then by all means use it, all the better.  Because I run 200 watts (or less),  I for one don't like the idea of placing too many devices 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 the performance of this wonderful antenna.

For the technical minded Windom builder, we opt for the 4:1 BALUN because it is; smaller, more efficient, weighs less, and less expensive to build.  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 Vee, supported between two masts, tower, or trees.  The Windom wire elements must not come in contact with any 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 80 thru 6 meters version is approximately 137 ft total length.      BUXCOM P/N 806136 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, 20, 10, 6, 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 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 4:1 (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.  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)
 

THUS; for 160 thru 10 Mtrs.........   

Long  Section;         468/1.8 MHz = 260  x  .64 =       166.4 feet.

Short Section;         468/1.8 MHz = 260  x  .36 =        93.6  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.  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 200Ω 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 (MM41 or MM41XV).  If you plan to run more than 1000 watts SSB into our Windom, we suggest you  request our Windom with the MM41XV Current BALUN rated at 1.5kW SSB.

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."   Perhaps many young hams ignore the multiband Windom antenna because of its sheer simplicity and may be thinking it is too good to be true. 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.

80 through 6 meter WINDOMs are completely assembled↓ 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.  Windom Model 806136   (with 4:1  BALUN), ↑WINDOM ↑ "without coax"                      Windom Model 806137   (with 6:1  BALUN), ↑WINDOM ↑ "without coax"                    Windom Model 806136L (with 4:1  BALUN), with Fifty ft. (50')  RG8X coax,                 Windom Model 806137L (with 6:1  BALUN), with Fifty ft. (50')  RG8X coax,                    Windom Model 806136C (with 4:1  BALUN), with One Hundred ft. (100') RG8X coax, Windom Model 806137C (with 6:1  BALUN), with One Hundred ft. (100') RG8X coax,  BUXCOMM Windoms are the choice of Hams, World Wide   WINDOM for 160 thru 6 meters completely assembled Click On any model number below, for more info, or to purchase. Windom model 166260 160 > 6 meters with 4:1 BALUN, L1+L2 = 260 ft. Windom model 166261 160 > 6 meters with 6:1 BALUN, L1+L2 = 260 ft. Windom model 166260L w/50 ft RG8X Coax, 160 > 6 meters with 4:1 BALUN, L1+L2 = 260 ft. Windom model 166261L w/50 ft RG8X Coax, 160 > 6 meters with 6:1 BALUN, L1+L2 = 260 ft. Windom model 166260C w/100 ft RG8X Coax, 160 > 6 meters with 4:1 BALUN, L1+L2 = 260 ft. Windom model 166261C w/100 ft RG8X Coax, 160 > 6 meters with 6:1 BALUN, L1+L2 = 260 ft.   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.

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.

Loop Antennas

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 4:1 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 MM41, 4:1 balun should exhibit an VSWR at resonance below 1.5:1.

Download 2007 Catalog

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.

1:2 BALUN: 50 to 100 ohms.  This Balun is suitable for feeding Ladder Line, Quads and loop antennas.

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.

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. 

1:9 BALUN: 50 to 450 ohms for coupling Asymmetrical to Symmetrical feeders.

1:9 UNUN:   asymmetrical to asymmetrical (unbalanced to unbalanced) Long wire antennas, Ground Plane`s, Verticals, and some types of  “beverage” antennas,.. etc.

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                        Bands/Coverage             Overall Lengths             BALUN

G5RV-16010              160 to 10 meters            208 feet  or  63 meters           MMG5

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