[ADXA] Homemade Antenna

Mon Dec 8 18:31:14 EST 2025

Jon,

I tried to find the message with your description of the antenna, but the
only thing I could find is the reply by Randy.  Very strange.  I was glad I
got to see it one way or the other, though.

I have heard of the Rybakov antennas, and you certainly seem to have yours
fine-tuned, especially for good results on 160.

Your writeup was also impressive.  That is good, complete information that
could go into a magazine article just as it is.   Add a couple of pictures,
and you're there.  Thanks for taking the time and effort to do such a good
description.
I only have one question so far - are your radials elevated or on the
ground?

73,
Dennis/RZ

On Sun, Dec 7, 2025 at 5:08 AM Randell Curtis, W5ZJ via ADXA <
adxa at mailman.qth.net> wrote:

> Jon, thanks for the write up and explanation of the antenna. I had already
> Googled the design, but your description of how to make it happen is the
> best I’ve seen. It just goes to show that a little research, ingenuity, and
> hard work can accomplish a lot.
>
> Very well done building and writing!
>
> Randy/W5ZJ
>
>
> On Sat, 6 Dec, 2025 at 10:21 PM, Jon W. Reynolds via ADXA <
> adxa at mailman.qth.net> wrote:
> To: adxa at mailman.qth.net
> Cc:
> For those interested in my home made antenna situation...spoiler alert and
> shortened version...I started with a Multiband Rybakov design and kept
> messing with it...
>
> Now, for the more detailed version: I described what I could remember in
> the evolution of what I have conjured up to an AI chat bot, and told it,
> that I want to document what I have done for those in the club interested
> in what I ended up with, and although I attribute my success to talking to
> real people, the chat bot took the liberties to describe and add
> information that I'm not necessarily smart enough to back up.... so that
> being said, if you are interested in the full read, continue on:
>
> # Evolving a Rybakov Vertical: A Homebrewer's Journey to 160m-2m Coverage
>
> ## Project Overview
>
> What started as a straightforward Rybakov multiband vertical antenna
> project evolved into a significantly enhanced design through iterative
> improvements. The result is an antenna system providing usable SWR across
> 160m through 2m, with confirmed performance on both FT8 and CW modes.
>
> ## Base Design Concept
>
> The project began with the Rybakov multiband vertical as the foundational
> design. However, rather than implementing a simple single-wire radiator, I
> opted for a more robust caged vertical configuration to reduce equivalent
> resistance and improve bandwidth characteristics.
>
> ## Radiator Construction
>
> ### Vertical Element
> The vertical radiator consists of four 12-gauge wires arranged in a cage
> configuration. The wires are maintained at proper spacing using 4-inch PVC
> pipe segments as insulators/spacers. This caged design provides several
> advantages over a single-wire element:
> - Lower effective resistance
> - Increased bandwidth on each band
> - Greater mechanical stability
> - Improved power handling capacity
>
> The vertical element is supported by three 11-foot sections of chain link
> top fence rail in the center, which serve dual purposes as both mechanical
> support and electrical connection to the wire cage Guy lines of paracord
> secured to neighboring trees provide stability for the vertical section.
>
> ### Feedpoint Configuration
> A 9:1 unun (unbalanced-to-unbalanced transformer) serves as the interface
> between the high-impedance antenna and the 50-ohm coaxial feedline. This
> impedance transformation is critical for achieving acceptable SWR across
> the wide operating frequency range, allowing the radio's internal tuner to
> handle the remaining mismatch.
>
> ### Capacitive Top Loading
> To improve efficiency on the lower bands, particularly 160m, I implemented
> an extensive top-loading system:
>
> **Phase 1:** Initial top hat consisted of approximately 100 feet of
> 12-gauge wire configured in a "T" arrangement.
>
> **Phase 2:** Expanded the top loading to approximately 230 feet of wire,
> maintaining the T configuration for improved capacitive loading and lower
> takeoff angles.
>
> The top-loading wire is supported by paracord guy lines and terminated at
> 30-foot top fence rail masts at each end of the T. These end supports are
> electrically insulated from the antenna wire to prevent detuning effects.
>
> ## Ground System
>
> A comprehensive radial system was installed to provide effective ground
> plane characteristics:
>
> - **40m, 20m, 15m, and 10m:** Quarter-wavelength radials for each band
> - **160m:** Seven 1/8-wavelength radials (eighth radial was canabalized
> for top-loading)
>
> This hybrid radial approach balances the practical limitations of
> installing full-length radials for 160m against the need for adequate
> ground plane performance.
>
> ## Performance Results
>
> The antenna system exhibits SWR of less than 3:1 across the entire
> operating range from 160m through 2m, allowing the internal antenna tuner
> in my Yaesu FTDX10 to achieve acceptable match throughout this spectrum.
>
> ### Confirmed Contacts
> While comprehensive on-air testing across all bands is ongoing, the
> following performance has been verified:
>
> - **FT8:** Successful contacts on multiple bands
> - **CW:** 160m contact confirmed with W5ZN in Cayman Brac, demonstrating
> effective low-band performance
>
> ## Construction Notes and Lessons Learned
>
> 1. **Progressive Enhancement:** Starting with a known design and
> incrementally improving it allowed for systematic performance evaluation at
> each stage.
>
> 2. **Mechanical Considerations:** The fence rail center support proved
> essential for maintaining vertical alignment, especially with the
> additional weight and wind loading from the extensive top hat.
>
> 3. **Guy Line Strategy:** Paracord provides excellent strength-to-weight
> ratio and weather resistance while maintaining sufficient flexibility for
> wind loading.
>
> 4. **Radial Compromise:** The use of 1/8-wavelength radials on 160m
> represents a practical compromise between effectiveness and available
> space. Performance appears adequate based on initial testing.
>
> ## Future Enhancements
>
> Potential areas for continued development include:
>
> - Completion of the eighth 160m radial
> - Systematic on-air comparison testing across all bands
> - Evaluation of additional top-loading configurations
> - Documentation of radiation pattern characteristics through reciprocal
> bearing analysis
>
> ## Conclusion
>
> This project demonstrates that thoughtful iteration on established designs
> can yield excellent results for the homebrewer. The Rybakov concept
> provided a solid foundation, while the caged vertical construction,
> extensive capacitive loading, and comprehensive ground system combined to
> create a versatile multiband antenna capable of operation from 160m through
> 2m.
>
> The ability to work DX on 160m CW and maintain consistent digital mode
> contacts across multiple bands confirms that this hybrid approach
> successfully balances theoretical performance with practical construction
> constraints.
>
> ---
>
> I would be happy to answer any further questions or field comments or
> ideas to improve or clarify if I can :)
>
>
>
> Jon
> KI5UCZ
>
>
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