No Counterpoise Speaker Wire Antenna
Itโs been a while since Iโve done a cheap speaker wire antenna, so hereโs another one for you. Back in the early to mid-2000s, an antenna commonly referred to as the โNo Counterpoise Antennaโ was making the rounds on the Internet. I thought I might give it another look.
The No Counterpoise Antenna is either a 25-foot or 50-foot length of two conductor wire with half of one conductor removed. Essentially, itโs a radiator fed through a balanced line feeder. The 25-foot version is said to cover 20M through 10M, while the 50-foot version is supposed to cover 40M through 10M. It was usually connected to a balanced tuner of some sort or sometimes fed through a 4:1 balun. It was typically constructed from zip cord or speaker wire. So, this is perfect for another speaker wire project. (Actually, I built the 50-foot version years ago, but I donโt recall ever putting it on the air.)
A picture is worth a thousand words, so here goes:
Iโve seen this antenna sometimes referred to as a Zepp. A true Zepp is basically a half wave radiator with a quarter wave balanced line matching section. Unlike a true Zepp, the No Counterpoise Antenna is non-resonant, so I guess itโs actually โZepp-ish.โ Because itโs non-resonant, a tuner is required for this antenna.ย
I did some extensive research into the origins of this antenna. (OKโฆ I just did a few Google searches.) Jeff Imel K9ESE came up with this design. I remember Jeff used to sell a high-quality version of the antenna on eBay. The reviews were generally positive.
Pete Millis, M3KXZ, is another name often associated with this antenna. I think thatโs how I first came across it. Pete once made a phased array from two 25-foot versions.ย
In the August 2020 edition of Ozark QRP Banner, the Four State QRP Groupโs newsletter, Terry Fletcher, WAรITP, had a nice write-up about it. He discusses his experience with both the 25- and 50-foot versions.ย
This antenna design has been around the block a time or two. So, thereโs no innovation here on my part whatsoever.ย
Construction
I happened to have a 25-foot roll of #18 awg speaker wire on hand, so this time around, I opted to buildโฆyou guessed itโฆ the 25-foot version.ย
Construction was about as easy as it gets:
- I split the speaker wire halfway and cut off one side
- Next, I twisted a loop at the end of the single wire and secured it with some Goopยฎ adhesive. As an alternative, you could just tie a loop at the top or crimp a ring lug over the wireโs insulation.ย
- I stripped and tinned the wires at the feedpoint and installed spade lugs. You can just strip and tin the wires, if you like.
- To keep the speaker wire from splitting further, I put some heat shrink tubing a couple of inches up from the lugs. I also added a dab of Goopยฎ in the middle of the antenna where one side of the wire was removed. All of this is completely optional.ย
Construction probably took me all of 15 minutes or so. That doesnโt include allowing the adhesive to cure overnight. However, the antenna was certainly usable without the adhesive and heat-shrink tubing I used. Iโm just prone to overkill.
On the Air
To test the No Counterpoise Antenna, I drove down to Ridley Creek State Park (US-1414, KFF-1414). Using my drive-on mount, I supported the antenna from a 28-ft Jackite pole. I used a homebrew 4:1 unun at the feedpoint and ran 15 feet of coax into the cab of my truck to my KX3 (5 watts, CW). I used the long side of the antenna as the radiator.
Before I got started, I checked to see how the tuner in the KX3 would handle the antenna. The KX3 easily found a 1:1 match on all bands from 40M through 10M. Just for the heck of it, I tried 60M and 80M. The KX3 was able to find a good match on those bands, too. (Thatโs not too surprising, given that I once forgot to attach my coax to an antenna, and the KX3 still found a match.) I doubt this antenna would work well on 60M and 80Mโbut stranger things have happened. I wasnโt able to try it, but Iโm sure the KX3 would be able to match it directly connected to the radio without the 4:1 and coax.ย
Band conditions werenโt very good, so this wasnโt an ideal test. Despite the mediocre band conditions, I logged 13 contacts during my short activation. Most of my contacts were on 40M. There was considerable fading on 30M and 20M, but I made a contact on each of those bands.
This was hardly a rigorous evaluation, but the 25-foot No Counterpoise Antenna got the job done. I need to give it another try, when conditions are better.
Anyway, if you have some speaker wire and a few minutes to spare, give this one a try and see what you think.ย
72, Craig WB3GCK