Editor’s Note: Over the next several months, OnAllBands will be featuring a series of articles from Harry “Trippy” Brown, AC8S, longtime amateur operator and antenna builder/tester who’s never let his visual impairment stop him from enjoying the hobby he loves. As the title of this series states, we hope these articles provide you with invaluable insights as you pursue your own successful antenna projects.
I’ve mentioned coiling several times in previous posts. Today, I’ll be exploring this topic in greater depth. To read the first 10 entries in this series, just enter “Trippy” in the OnAllBands search box above.
Coiling: a New Revolution in Building Dipole/Inverted-V Combo and End-Fed Antennas
Note: My thanks to Barry, KU3X, for giving me the idea to use coiling, which will change how dipole/inverted-V combo antennas and end-fed antennas are put up—FOREVER!
For many years, hams have been able to put up dipole/inverted-V combo antennas or end-feds because they had room to string the antenna all the way out. But today, more and more operators face restrictions that prevent them from deploying these antennas in this manner. This includes:
- Hams who live in space-restricted areas, where they have very little room
- Hams who live in HOAs, where regulations preclude these antennas and putting them up outside draws complaints from neighbors about their unsightliness
- Hams who live in nursing homes or group homes which don’t have the space to string these antennas all the way out
Unfortunately, so many hams—due to these situations—had to leave the hobby because they had no way to get on the air. But coiling changes everything. So if you know any hams who had to leave the greatest hobby in the world, tell them how coiling lets you build a dipole/inverted-V combo or end-fed antenna that works as if it were strung all the way out. It’s incredible! Coiling can enable you to get out on all bands, 160 through 2 meters!
How does coiling work?
With coiling, you still have two legs on the dipole/inverted-V combo or end-fed—that hasn’t changed. But what has changed is you have a coil exactly half way between the balun and the end of each leg of the dipole/inverted-V combo, or six feet away from the unun on the wire leg of the end-fed antenna.
VERY IMPORTANT: With coiling, you do not add the coil of wire. You make the coil out of some of the wire that’s already included on the antenna.
My friend, Brian, N8MNX, who has been a ham since 1990, had never been able to be on the air doing what hooked him on becoming a ham in the first place—getting on 80 meters and checking into nets. So here’s what I did.
I put up a half wave dipole/inverted-V combo on 80 meters for him. It was 131.8 feet, including the 3 inches on the ends of each leg of the antenna. However, I had only 43 feet of room to stretch out the antenna horizontally on his balcony, so I coiled the rest of the wire, which already was part of the antenna, at each end of the antenna. Please note that this was the wrong way to do it.
I was running 100 watts on his Kenwood TS-570. I got on 80 meter CW and made several contacts, but then I got on 80 meter phone running 100 watts. I answered a CQ from a ham in 5 land somewhere. He said, “I hear someone in there, but I cannot pull you out, you’re too weak.”
So I posted my situation and where the coils were located to the antenna forum on QRZ. Barry, KU3X, posted this fabulous response: “Trippy, you never want a coil at the end of an antenna when you shorten an antenna. The wire closest to the feed point of the antenna is the current portion of the antenna and that does the most work. Instead, you want the coil right in the middle of each leg, halfway between the balun and the end of each leg of the dipole/inverted-V combo. The very first shortened one I ever made many, many years ago was done just this way and it worked great. The middle of the antenna leg is the best place for a loading coil. You should get out a lot better after each coil is at the halfway point on each leg, between the balun and the end of each leg.”
Note: For those of you who want to try this idea for portable use, let me know how it works!
So yours truly and ham friend Rick, WO8M, went out on Brian’s balcony to the dipole/inverted-V, measured the length of the left leg between where it connected to the balun and the end insulator, and marked it with tape right at the halfway point on his aluminum balcony railing.
Then I unhooked the end of the left leg from the end insulator and started making a coil. I kept coiling to the right until I got to the halfway point, where the tape marker was. Keeping my hand around the coil so the coil would not get away from me (but still had enough looseness), I had Rick pull just enough wire back to the left so he could again wrap three inches of wire around the end insulator at the end of the left leg.
Then, I put a two-foot-long tie wrap through the hole in the middle of the coil and pulled it tight. This completed the left coil. My friend and I followed the same steps for the coil on the right leg, this time keeping the coiling to the left until I got to the halfway point between the balun and the insulator end of the right leg.
Would it work?
I plugged the coax into the SO-239 connector on the balun. Then I plugged the PL-259 connector into the radio. I got on 80 meters at the exact center of the band, 3.750. I checked the natural SWR without trying to tune the antenna. To my amazement, it was 1.7 to 1. I went to 3.501 and the SWR was 1.1 to 1. At 3.600 it was 1.2 to 1; 3.800 was 1.7 to 1; 3.900 was 1.7 to 1; and 3.999 was 1.7 to 1. It was absolutely incredible—low SWR across the entire band!
Now it was time to try to make a contact! Fortunately, it was the weekend of the CQ WW WPX (WPX stands for worked all prefixes) contest, so I knew there would be a lot of activity. I went down to 3.600 and went up the band and heard the first station, ND8DX, on the Ohio/Kentucky border! My heart was racing. Would he hear me and my hundred watts? On my first call I heard, “Alpha Charlie 8 Sugar.” He got me on the first call and gave me his report! This antenna got out over 300 miles and made a contact. I cannot tell you the joy Brian and I felt when ND8DX said my call sign back to me and gave me my report!
Would the half wave dipole/inverted-V combo work on other bands?
I went to 40 and heard KB0EO in south central Minnesota. It took two calls, but he got me, so now I knew it worked on 40. But what about 20 meters (also known as Kilowatt Alley), with me and my 100 watts on Brian’s 570? I went to 20 at about 9 o’clock that Friday night, March 26, 2021. I heard NM7C in Oregon City, Oregon, but would he hear me? I called him and he got me on the first call. It worked!
Then I went to 28.850, the exact middle of 10 meters, and pressed the tune button on the 570. It tuned the antenna below 3 to 1! I now knew that this antenna would work wonderfully on 10, 20, 40, and 80 meters! The only band where the SWR was above 3 to 1 was 15.
Next Week’s Blog Post
What about making a dipole/inverted-V combo without soldering? Also, what about making one if you’re blind? Can it be done? Yes, it can. I’ve done many of them, and I will show you how to do it, step by step, next week. Stay tuned.
Questions? Comments? Reach me at hebrown3rd@gmail.com.
