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KJ6ER Antennas

December 2025

Introducing the New KJ6ER

2-Element Parasitic ChallengerArray with

+2 dB More Gain and 8 dB Front-to-Back

Dear Fellow Portable Antenna Geeks 😀

In this month's newsletter, I am excited to introduce
the new 2-Element ChallengerArray featuring a parasitic director in front of the driven element for almost +2 dB more directional gain over a single Challenger with over 8 dB of front-to-back!



The Challenger is an off-center fed (OCF) halfwave vertical antenna utilizing a 25' telescoping whip, 4:1 unun and a short linked counterpoise wire. It covers 20M-6M with a takeoff angle of only 21 degrees. It is an excellent antenna for both regional and DX communications. It is rapidly becoming one of my most downloaded antenna PDFs due to its outstanding performance and fast deployment in the field.



The 2-element ChallengerArray expands the antenna system with a single driven element (Challenger with 4:1 unun connected to a feedline) and a parasitic element as a director in front (not connected to a feedline or with an unun). The driven and parasitic elements each have its own linked counterpoise which is identical in design to a single Challenger antenna.



If you do not have the time or ability to build a Challenger antenna, you can purchase a variety of assembled Challenger configurations on Etsy: Challenger 2-Element Parasitic Array System, the Parasitic Director stand-alone, a single element Challenger Antenna System with a 25' Chameleon™ telescoping whip and 16" stainless steel spike, a Challenger CORE without the whip and spike, or a Challenger Linked Counterpoise Wire stand-alone.



Almost 100 products have already been sold at the
J-Systems Store on Etsy during its first four months and have received all 5-star reviews from buyers!

KJ6ER Challenger
KJ6ER ChallengerArray
Challenger 2-Element System on Etsy
KJ6ER Challenger CORE on Etsy
Challenger Parasitic Radiation (Side)
Challenger Parasitic Radiation (Top)

How does it work? - The electromagnetic field from the driven radiator energizes the nearby parasitic element by inducing current within it through mutual coupling which, in turn, reradiates the driven element signal both constructively and destructively forming a unidirectional semi-cardioid radiation pattern. 



Where constructive, the parasitic element reinforces a portion of the forward driven signal for increased gain. Where destructive, it cancels some of the rear driven signal to create a null forming beneficial directivity and front-to-back characteristics. This radiation pattern helps minimize unwanted signals and noise from the back of the antenna system.

Challenger Parasitic Director Length

After dozens of computer modeling iterations in 4NEC2, an optimal director length (as a % of the radiator) was calculated, as well as the appropriate physical spacing between the radiator and the director (relative to the operating wavelength). The computer model ultimately determined that the parasitic director should be 93% of the radiator length and is spaced 0.11 λ in front of it.

Not only does this new 2-Element Parasitic ChallengerArray provide additional gain and front-to-back for directivity, it also features low SWR on each of the bands with very wide bandwidth. For example, the entire 20M band from 14.000 MHz to 14.350 MHz is typically under 1.50:1 SWR so the operator can switch from CW / Digital to SSB without retuning the parasitic antenna system or using an external tuner.

ChallengerArray 20M SWR Sweep

The 2-Element Parasitic ChallengerArray can be found as a new 5-page section beginning on page 15 in the December revision of the Challenger OCF Halfwave PDF. Download the Challenger PDF today and start building the array!

What's Coming - In January, I will be taking a fresh look at my best low angle DX antenna: the 17M-10M Dominator end-fed halfwave antenna with an 18° takeoff angle for excellent continental and worldwide DX communications. And what makes it even more exciting is adding a parasitic director in front of it on a rotatable homebrew PVC structure to target desired geographies on your great circle map!



The DominatorArray is a portable, resonant 2-element parasitic halfwave vertical beam antenna covering the 17M-10M bands utilizing two 25’ whips: one end-fed by a 49:1 or 56:1 unun (transformer) on a tripod, and the other as a parasitic director on a supporting rotatable PVC structure. If two 17’ whips are used instead, the array covers the 12M-10M bands. Time to chase that DX on the upper bands before it goes away as the 11-year solar cycle wanes!

As we move into the 2025 Holiday Season, buy yourself a well-deserved gift of a fresh set of high quality ABR coaxial cables. If you use my callsign KJ6ER as the coupon code at check-out, you will receive a nice 10-20% discount on your total order!

ABR Coaxial Cables

Until next time, keep having fun out there! Building ham radio antennas is our last homebrewing frontier and I am dedicated to helping you do so successfully! See all my free antenna design plans at the cloud links below.



If someone forwarded this email to you and want to be added to my antenna geeks email list, send me a message and you will be the first to receive new KJ6ER antenna designs and updates! I am also available to present my antennas to your Amateur Radio Club via Zoom. Let me know if they are interested! 



As always, feel free to reach out to me if you ever have any questions, I'd be happy to help you! 🙂 73 KJ6ER, Silicon Valley

My mission is to design efficient and effective portable antennas for the every-ham that focus on the optimal integration of performance (high radiation efficiency), elegance (speed and simplicity of deployment) and convenience (ease of transport and storage). These designs are always shared for free with the global amateur radio community to encourage more radio operators to homebrew their own portable antennas. 

KJ6ER Antennas

Cloud Drive File Links (KJ6ER):

Greg Mihran, KJ6ER

Campbell, California

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