Availability of Mag Loop and other stuff...

Jack, W8TEE


The results right now are modeled using the usual Pacific66 app. However, we do plan "real" tests in an attempt to get some useful data. Our reference antenna will likely be an 80-10M EFHW which we both use. Al also has a vertical that we might test against. However, the EFHW is always available; not so with the vertical.

We read in a paper that someone added a ground plane and said it "made a difference", whatever the hell that means. Anyway, because of that, we want to try it and see if it does have an impact. We have already noticed that the shape of the feed loop makes a difference, as does its position in the vertical plane. The effect is small, but real.

Al and I have talked about this a lot, and our feeling is to publish the results of the "Double-Double" as a construction article. (I want to call it the "Luggable Double-Double" but Al's not happy with that.) There are controllers out there (Loftur Jonasson) so my feeling is that will be kept for the book only. Also, it will be somewhat unique in that we hope to add a TFT display that shows the SWR in realtime as a plot. We have arranged to have all of the projects' PCB's available at a reasonable price.

Al and I are writing the book in a strange way. We are going to finish it before signing with a publisher. The reason is because I know the time pressures that editors put on authors with respect to deadlines and we want to get this right rather than to market fast. Our TOC has 18 chapters, of which the first 4 are really setting up the software for the Arduino, Teensy, STM32, and ESP32 ┬ÁC's and giving the beginning reader enough C instruction to read our code (and shoot themselves in the foot a few times?) We see 12 projects in the book, some of which (e.g., the ML) are two chapters--construction and software. Some are "end products" (e.g., the ML, a different antenna tuner, CW messenger, CW decoder, CW Tutor) while others are test equipment (e.g., programmable power supply, AC voltmeter, signal generator). The last chapter is on using what you've built to troubleshoot a receiver. We think it will be a very unusual, but useful, book. Our goal is to have it done by the fall. We currently have 9 chapters done.

Long answer to a short question...

Jack, W8TEE

On Saturday, June 1, 2019, 12:01:46 PM EDT, Alan de G1FXB via Groups.Io <g1fxb@...> wrote:

Hi Jack,

Sounds like you are on to something special with 90% and even the 40% are impressive figures.
(Noted that they are modelled?? efficiencies at this point in time, here's hoping with can you can achieve something approaching in practical tests.)
To what reference antenna (also at the same modelled height to compare like for like) ?

Interested in your comment the trials of a counterpoise,
Previous papers indicate loop type antennas were considered a free space antenna requiring no ground plane / radials
I guess it's the feed / matching & counterpoise is where the magic happens?

As it's using an auto tuner is the write-up destined for your new book is there an ETA, or another perhaps magazine article release?

(One gotcha about some of the previous, (not your) small "miracle" antenna's.
Check it's actual the antenna doing the radiating and not the feed line, or counterpoise even the mounting pole has being known to be "accidentality" hot with RF.
(However disguised, generally any antenna employing a braid breaker / balun in the coax away from what they make you believe is the feed point or suggested feeder or support lengths perhaps warrants a second look.))

regards Alan

On 31/05/2019 18:45, Jack Purdum via Groups.Io wrote:
We are also trying to assess other factors, too, such as a counterpoise and its affect on performance. We may find that these "other factors" play no significant role in the antenna's performance. Still, learning that something doesn't matter is as helpful as learning what does matter.

Jack, W8TEE

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