One antenna that has garnered a significant following among POTA operators is the POTA PERformer designed by Greg Mihran KJ6ER. In essence it is a raised quarter wavelength vertical with 2 above ground radials. A simple idea that Greg has engineered into a rapid deployment, highly efficient, multiband, portable antenna. Greg has backed up his design with a detailed analysis supporting the claimed high performance characteristics. Many operators, including myself, have built and used the POTA PERformer and can verify that it is indeed a very good antenna.
NB: I have already covered the POTA PERformer in a recent post and concluded that just a single raised radial was sufficient. However, after reading Greg KJ6ER’s analysis in more detail I am now convinced that using 2 radials raises the antenna’s efficiency.
There are three innovative antenna designs in KJ6ER’s kit bag. The other two are both half-wave designs. The POTA Challenger is an off-center fed half-wave that supports 20m and up; the Dominator is an end-fed half-wave that supports 17m and up. I have not tried to build a Dominator (yet) since most of my own POTA operations are on 20m, but the Challenger caught my attention so much that I had to build my own version.
When I first looked at the design I was completely bewildered. It comprises a 25ft telescopic vertical whip with a wire counterpoise, part of which lies directly on the ground. Does that look like a typical half-wave antenna, I thought to myself? I had never seen anything like it before so my skepticism was aroused. After exchanging a couple of emails with Greg I was encouraged to go right ahead and build one in the hope that actually using it to fire RF up to the edge of space and back would bring about a better understanding of this strange new electromagnetic beast.
Well, I did build my own version of the Challenger, massaged the design a few times and came up an antenna that got me some very encouraging signal reports from the land of far, far away. Of course, this blog is called “Ham Radio Outside the Box” so, just like Frank Sinatra, I “did it my way”. To learn more please read on.
The Ham Radio Outside the Box version of KJ6ER’s Challenger
First, I would like to wholeheartedly endorse the work of Greg Mihran, KJ6ER. One might have expected him to be selling commercial versions of his antennas, but instead, he has published detailed build instructions and readily responds to emails from fellow hams. That is the true spirit of our hobby; hams helping hams.
of KJ6ER’s Challenger antenna
It wouldn’t be fair to even refer to my own version as a “Challenger”. Instead I will just say that it is inspired by KJ6ER’s Challenger. It follows the same ideas but implemented in a different way. I don’t own a 25ft telescoping whip and didn’t really want to have to buy one, so I decided to incorporate a wire radiating element, supported by my 7-meter Spiderbeam telescoping fiberglass pole.
Then, whereas the Challenger is a multiband (one band at a time) antenna supporting every HF band from 20m and up, I looked at my own POTA activations and realized that I rarely stray from the 20m band. Maybe a monoband antenna is all I need. That keeps the design sweet and simple. I like sweet and simple when I am out in the Big Blue Sky Shack. I did wake up one morning with an urgent need to rush down to my basement shack and sketch out an idea for a multiband version that still uses wire elements. More information on that idea later in this post.
I took the dimensions of the radiating element and counterpoise wires directly from KJ6ER’s document. Of course, a wire – in this case teflon covered 20awg multi strand wire from BNTECHGO almost certainly has a slightly different velocity factor from a tapered stainless steel telescoping whip as I discovered when the antenna was erected. It was necessary to shorten both wires a little to bring the antenna into resonance in the CW portion of the band.
Another gotcha is the height of the feedpoint. It has a quite dramatic effect on the tuning. The first iteration of the Ham Radio Outside the Box version used a taller pole. The wires were trimmed to obtain a 1.07 SWR, but when I substituted the shorter pole and re-erected the antenna with the feedpoint only 12 inches above the ground, the SWR shot up into the stratosphere.
NB: KJ6ER built a “backpack” version of his Challenger in which the feedpoint is lowered to 12-inches above ground. I found this height allows me to use my 7m Spiderbeam pole and also makes it easier to orient the counterpoise so that it makes good contact with the ground.
After further adjustments of the wire length a low SWR was restored. I ended up with 22ft/6.7m for the radiating element length and 5.5ft/1.7m for the counterpoise. If you were to reproduce this design your own dimensions might be different; an antenna analyzer is a very useful tool to have.
A multiband version?
The original Challenger uses a telescopic whip so switching bands is quick and easy by simply adjusting the length of the whip. The counterpoise length must also be adjusted, but this is accomplished by means of a linked wire.
I have not built a multiband version of the Ham Radio Outside the Box interpretation of the Challenger but I have entertained two ideas for how to accomplish this goal. First, simply using links in the radiating element wire might be the simplest and easiest way to do it. There is a second possible way and that is to employ parallel radiating element wires in the manner employed by the DX Commander vertical antenna. If you are not familiar with the DX Commander, do a web search on the name and you will see what I mean.
I am so impressed with the portability, efficiency and small footprint of this antenna that it is going to replace some of the other SWAs (Simple Wire Antennas) in my field operations kit bag.
Same Pole, Different Wire
The title of this post is “Two Resonant Simple Wire Antennas for POTA” so what is the second one? I had built my first version of the POTA PERformer using an MFJ-1979 telescoping 17ft/5m whip mounted on a tripod. If I wanted to do a field outing carrying both this and my own Challenger variant I would have to carry my Spiderbeam pole and the tripod. Since I often stray far from my truck when operating out in the Big Blue Sky Shack I need to economize on the amount of gear I have to carry. Maybe I could build a wire version of the POTA PERformer that could be supported by the 7m Spiderbeam pole.
I realized I already had such a beast – a super light QRP version I built many years ago. Now I needed to copy that idea and build it for QRP or QROp (20-30 watts). So, the new SWA Ham Radio Outside the Box version of the POTA PERformer was born, and again it is a monoband 20m antenna.
As we can see from these images, the simple wire version of the POTA PERformer adapts very well to being supported by the compact, lightweight Spiderbeam pole.
The vertical radiating wire is attached to a standard 3/8x24tpi to SO-239 adapter. The two radial wires connect to the adapter via a 2mm banana connector so they can be separated for storage. The female 2mm connector is crimped and soldered to a 3/8 inch ring connector.
The image also shows the ham-brewed-by-me common mode current choke made from an FT240-43 ferrite toroid core wound with several turns of RG-58 and tested with a nanoVNA to ensure it is doing its job.
Now I only have to carry the Spiderbeam pole and two small freezer bags containing the wire elements for both the PERformer and Challenger variants and I have choices when I get to my operating site. Which to choose? I highly recommend reading KJ6ER’s documents, linked below, especially Greg’s “Antenna Primer”. Greg explains everything you need to know so much better than I ever could.
Cloud Drive File Links (KJ6ER):
- YouTube™ Interview with Michael Martens, KB9VBR –
youtube.com/watch?v=cClmWBYzNaE - ARRL™ QST 2024 Antenna Design Competition –
bit.ly/AntennaDesignCompetition - ARRL™ QST September 2025 PERformer Article (First Page) –
bit.ly/QSTSeptember2025FirstPage - KJ6ER Antennas Primer –
bit.ly/KJ6ERAntennasPrimer - PERformer 40M-6M Quarterwave Vertical –
bit.ly/KJ6ERPERformer - PERformer 40M-6M Quarterwave (Assembled, Etsy) –
bit.ly/KJ6ERPERformerKit - Challenger 20M-6M OCF Halfwave Vertical –
bit.ly/KJ6ERChallenger - Dominator 17M-10M EF Halfwave Vertical –
bit.ly/KJ6ERDominator - Dominator 17M-10M EF Halfwave 2-Element Vertical Beam –
bit.ly/KJ6ERDominatorBeam
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Ham Radio Outside the Box 
Hello John,
Good post. I just finished up an activation, and this gives me some things to try next time.
I am curious, what connector are you using to attach the radiator and counterpoise to the SO-239? I love that it has screws so you can just attach a prong connector and tighten it up. It beats the hack approach i take to this and sure would save some time.
Thanks- Jack W9TNC
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Thanks Jack. Sorry to hear you had difficulty posting your comment; I don’t know what happened there. On my PERformer antenna, I use a standard 3/8×24 to SO-239 connector which is often referred to as a CB mirror mount. The vertical radiator wire is terminated in a ring terminal and is crimped, soldered and reinforced with layers of shrink tube. This mounts onto the 3/8×24 thread and is secured with a 3/8×24 nut. The counterpoise wires are connected via 2mm banana connectors. The female banana plug is soldered to the counterpoise wires; the male banana jack is crimped and soldered to another ring terminal that is clamped to the SO-239 with a flat plastic washer to insulate it from the radiator wire.
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Nicely done. I also do POTA mostly on 20m and appreciate your designs.
Your HROTB version of the Challenger is similar to the Rybakov or 3/8 wave vertical. A 25 – 26’ radiating element, 4:1 UNUN and 4 untuned radials on the ground. The Challenger design is tuned to provide a good match and high overall efficiency.
Extending the radiator to 29’ with 9:1 UNUN turns it into an End Fed Random Wire (EFRW) that works well on 40-10m with a tuner. A few more feet and 49:1 UNUN turns it into a 20m EFHW. Both work with a 10m mast.In my experience the EFHW is great for DX; the EFRW is better for extended portable operation where you sometimes need 40 or 15m; and the POTA PERformer is best for rapid deployment. Enjoy!
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Thanks, good suggestions. I have tried the Rybakov and EFHW and agree that both work well.
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I enjoyed your discussion and want to share with you one of my setups. I too use a 7 meter Spiderbeam mast for portable operations as well as using hamsticks mounted on a light tripod or my motorscooter (but not while driving). With my Spiderbeam mast I use 17.5ft (5.33 meters) of speaker wire as the driven element and approximately 3 feet (one meter) of wire as the counterpoise. I can link several lengths together depending on the ground. They are connected to an LDG 9:1 unun and LDG common mode choke. I usually have about 30ft (10 meters) of RG58 coax that connects the antenna to my radio. I use a portable Antuner AT-1000M Pro as my antenna coupler (aka “tuner”). It is velcroed on to my Yaesu FT-891. The coupler is automatic, very light weight and has a self-contained battery. Wtih this setup I can match the antenna to the radio (ie “tuned” but we know the antenna is not tuned/resonant) on 10 meters to 40 meters. Being so short, the antenna is not very good on 40 meters. It works. I have also tried a 4:1 unun, but I found the 9:1 unun was better to match across all bands.
I just discovered your website/blog, so I have some catchup reading to do. 73! David SV0SGS
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Thanks for the description of your antenna David. I am impressed that such a simple arrangement works for you. I would have thought that a 1 meter long counterpoise would be too short. Have you measured the R+jX impedance on each band? That might reveal why the 9:1 unun works better than 4:1. If the impedance is high the 30ft coax may be transforming it to a lower impedance at the tuner.
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Hi! This antenna design was suggested by “Salty Walt” who has the YT channel “Coastal Waves.” A 17.5ft driven element and a (approx) 3ft counterpoise attached to a 4:1 or a 9:1 unun, and of course with an antenna coupler (aka “tuner”). He operates mostly near salt water on the beach. I live on a very small Greek island, approximately 150 meters above sea level. The ground is dry and rocky. The antenna works, certainly for 10 to 20 meters, including WARC and CB. The feed point is not quite 2 meters above ground. I did lengthen the counterpoise a little. That helped me get a match on 12 meters and 17 meters. I will check the R and X parameters. I have a good antenna analyzer. I was at my shack today (about 200 meters away and above our house). Reception on 40 meters was excellent. I have no RFI around me for at least 200 meters in any direction. Everything powered by 12 VDC. Solar panels and charge controller don’t present any noticeable interference. I use only wire antennas of various designs. I like experimenting.
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