New_Carolina_Windom_Antenna

The New Carolina Windom

The New Carolina Windom HF Antenna

The New Carolina Windom HF antenna uses a horizontal, OCF element and with balun / choke spacing, will radiate on the vertical feed line space between, the balun and choke. The Carolina Windom uses a ratio of 37.8% for the short horizontal element and a ratio of 62.2% for the longest horizontal element.

The New Carolina Windom is, a Half Wave length antenna at it's total length and can be used on other harmonically related bands without a tuner. The New Caroline Windom can be setup to run on 160, 80/75, 40 or any other band using the calculation formula below.

468 / Freq. = length

Total length * 37.8% = short side

Total length * 62.2% = long side

Vertical length @ 4:1 ratio = band meter / 4 = Balun to Choke spacing

In the image above, Mr. Carlson rounded up the total length of the antenna to the nearest foot (i.e. 65.9' to 66') for, an antenna cut for 7.1 MHz (40 Meters). To make things a bit more accurate, the measurements below only round the fractions of an inch to the nearest inch using 1/2” as the dividing point.

You always want to use judgment when cutting wire for an antenna, keeping in mind the raising and lowering of your resonant point based on, cutting too short or too long. Normally, you would want your lowest SWR (resonant point) in the middle of the band; across all bands on a multi band antenna. Cutting will move your resonant point up the band and adding will move it down the band.

1.900 MHz (160 Meters) Band Center

468 / 1.9 MHz = 264.315

short side length: .378 ( 37.8% ) x 264.315 = 99.91107' (99' 10 15/16”) 99' 10”

Long side length: .622 ( 62.2% ) x 264.315 = 164.40393' (164' 4 55/64”) 164' 5”

Vertical length @ 4:1 ratio = 160 meters / 4 = 41'

3.75 MHz (80/75 Meters) Band center

468 / 3.75 MHz = 124.8'

Short side length - .378 (37.8%) x 124.8 = 47.1744' (47' 2 3/32”) 47' 2”

Long side length - .622 (62.2%) x 124.8 = 77.6256' (77' 7 1/2”) 77' 8”

Vertical length 4:1 ratio 80 meters / 4 = 20'

3.9 MHz (80/75 Meters)
468 / 3.9 MHz = 120'
Short side length = .378 (37.8%) X 120 = 45.36' (45' 4 5/16”) 45' 4”
Longest side length = .622 (62.2%) X 120 = 74.64' (74' 7 11/64”) 74' 8”
Vertical length 4:1 ratio = 80 meters / 4 = 20'

7.1 MHz (40 Meters)

468 / 7.1 MHz = 65.9'
Short side length = .378 (37.8%) X 65.9 = 24.9102' (24' 10 59/64”) 24' 11”
Long side length = .622 (62.2%) X 65.9 = 40.9898' (40' 11 7/8”) 41' 0”

Vertical length 4:1 ratio = 40 meters / 4 = 10'

The first thing you will need is a 4:1 voltage balun like the one pictured below. You can either, purchase a made one or make one your self. I chose to make my own and used two, FT240-31 toroids which, were epoxied together. I wrapped the toroids with twelve turns of AWG 14 motor winding wire, encased in silicone tubing using the method pictured below. I have also used other materials to build and encase the balun as well although, I have stayed with the toroid type.

I found a water proof, project box online and drilled it out for all the fittings I wanted to add to it. I used an SO-239 (5/8” hole) so, I could add and remove a coax feed line in the field easily. I decided to use AWG 12 THHN stranded electrical wire for the horizontal elements and RG-8X for the feed line. Two Rubber Grommets for 9/16" Hole Diameter and 1/8" Material Thickness, 1/8" ID, were used to help keep out water in case it rained.

I cut 80' of 3/16” Dacron rope and ran it straight through the top hole (5/32”), in the box; tight fit, to keep out rain. I added two quick disconnects to the end of one side of the rope and hung it up at six feet. I added another quick disconnect to the other side of the rope and hung it up at six feet and pulled the rope tight with a pulley line.

Using the short element side first, I calculated where the balun box would need to be placed on the rope (80' – 66' = 14' / 2 = 7' + 25' = 32'). The center of the box was placed at 32' then, two all plastic zip-ties were added to the rope, inside the box so, it would not slide out of place.

I added the short wire element through the grommet and left enough slack for soldering the balun in later. I wrapped the wire around the rope toward the end, adding a zip-tie every 3' feet or so with one at the end leaving 4” of wire hanging over. Then I did the same thing for the long wire element side.

Then, I dropped the antenna down and took it inside, to solder in the balun. Once, the elements and SO-239 was soldered into the box, I took the antenna, back outside and hung it up again. I added a choke to the coax feed line at the balun box with 3 ferrite snap on beads. The RG-8X was 75' and was connected to the SO-239 and then, I connected the other end to the Mini600 antenna analyzer to, see how it checks out.

Below are some screen shots of the bands.

NOTE: After I tested all the bands, I did make some contacts with only, 100 watts and the internal tuner of the Icom IC-7300. I only used 20 meters on both days. On Jan. 1st, I worked Julie, KB6DRB, in Riverside, CA (2225 Miles). and on Jan. 2nd, I worked Scot, N6ZT, in Los Angeles, CA (2275 Miles). I also made contacts in NY, AR and OH. Needless to say, the antenna works and can be matched with an antenna tuner. I used an MFJ-969 although, a little touchy (tight) to tune, It did get me on other bands and I was able to make other contacts but, not as far as Califonia. Also, I was able to make some contacts on two, local repeaters, on the 2 Meter band, using my BaoFeng F8-HP walkie talkie, connected to the windom, as well! When, I have a chance to get more screen shots, at heights up above 15', I will add them to this page.

01/01/2021		01/02/2021
80 meters @ 5' Choke @ 0' from balun		80 meters @ 15' Choke @ 10' from balun


60 meters @ 5' Choke @ 0' from balun		60 meters @ 15' Choke @ 10' from balun


40 meters @ 5' Choke @ 0' from balun		40 meters @ 15' Choke @ 10' from balun


30 meters @ 5' Choke @ 0' from balun		30 meters @ 15' Choke @ 10' from balun


20 meters @ 5' Choke @ 0' from balun		20 meters @ 15' Choke @ 10' from balun


17 meters @ 5' Choke @ 0' from balun		17 meters @ 15' Choke @ 10' from balun


15 meters @ 5' Choke @ 0' from balun		15 meters @ 15' Choke @ 10' from balun


12 meters @ 5' Choke @ 0' from balun		12 meters @ 15' Choke @ 10' from balun


10 meters @ 5' Choke @ 0' from balun		10 meters @ 15' Choke @ 10' from balun


6 meters @ 5' Choke @ 0' from balun		6 meters @ 15' Choke @ 10' from balun


2 meters @ 5' Choke @ 0' from balun		2 meters @ 15' Choke @ 10' from balun


1.25 meters @ 5' Choke @ 0' from balun		1.25 meters @ 15' Choke @ 10' from balun


70 Centimeters @ 5' Choke @ 0' from balun		70 Centimeters @ 15' Choke @ 10' from balun

More to come soon!!!