Man I went off the rails in the last blog. Sorry about that this may be more winding still. It is earlier in the morning now, and hopefully I’ll make more sense. (Kinda doubt it!)
On with the discussion:
Portable operations require a different mindset. Things need to be easy to put up and takedown providing maximum functionality with a minimum of work. “Let’s get on the air already” is commonly heard after 10 minutes or so of setup. This is the goal, to be setup and running on any band between 6 or 10 and 80 meters in about 10 minutes having a resonant antenna.
It is possible or should be. The Wolf River Coils (WRC) multiband vertical and others like it are the best possible solution. They are easy to setup, adjust easily and connect to the radio with relative ease. Takes some practice, a black sharpie and antenna tuner to get the rhythm of the unit. Not least of these are the radial system.
The WRC vertical comes with 3-33foot radials. Even they say more is better. K8MRD has a video showing what happened when he used 15 – 2.5 meter and 3 – 10 meter radials on the WRC to host a POTA activation as part of his experimentation.
This article explains what happens over saltwater with radial length. It is important because the message is the same shorter and more radials is a good thing.
This is one of my favorite radial articles and has helped color my thinking on the subject.
Then I ran across this article on eHam Net. “The distance between your radials at their outer most tips should be 0.05 wavelengths or less.” This was enough to make me loose my mind. It basically states that “the more the better and the longer the better. In addition the longer the radials the more radials you can use efficiently. However, for a given radial length there is a point beyond which you are pretty much wasting your time; and for a given amount of wire there is an optimal way to use it.” What????
So now I am really confused. For portable ops, this tells me we need to have multiple radials of given lengths. Based on the Ventenna experiments, as mentioned in the previous post, 3 radials are optimum per band. This gets me thinking, I got side tracked by the 0.05 wave lengths and tried to make the radials 0.05 long.
The numbers made little sense so I took a break and did some work. on coming back I reread, The Mystery of Radials, this reminded me that experimentation has shown radials of 1/16th wave length can show respectable performance. I mis took it for .10 wave and computed lengths accordingly for 10m 20m 40/15m and 80m, getting 1-2-4-8. This reminded me of squares and the Fibonacci sequence.
If you want to read more about it Wikipedia has this article. (Excuse me my STEM is showing) It popped into my head that we could set up radials using the pattern. I works in nature why not radio?
Then it occurred to me that this would not work. It would be directional, probably on the opposite side of the radials. (have to experiment with that) Then I remembered the Ventenna experiments. If 3 radials are optimum for a vertical on band X, why wouldn’t the same be true for band Y, or band Z or band N? And because the numbers would represent a Fibonacci like set, why not use a 120 degree X3 setup for the radials spaced an equal wavelength apart?
The experiment, once I have all the parts, will use 3 radials for each band at 1/16 or .0625 wave length spaced at 120 degrees approximately. Each set will have 1 – 0.625 m, 0.9375, 1.25 m , 2.5 m , and 5 m, spaced at degree intervals from the legs of 24 degrees. The 5m already exists in the WRC kit. As a part of the experiment the 3 – 33 ft radials that come with the WRC will be the control. I’ll make a second set of 18 – 2.5m radials to test as a counter point to K8MRD radial test. All testing will include the 10m, 12m, 15m, 17m, 20m, 40m, and 80m bands.
73 kf7sfu
David Campbell KF7SFU 