On 7/20/19 10:50 PM, Grant Saviers wrote:
I think the topic "resonance of yagi elements" has a total attention in
publications of about zero. Then the topic, "coupled resonances of yagi
elements" has substantially less coverage. With a big stack it is
interesting to watch how turning one affects all others.
It has zero attention in ham publications. I can assure you it has a
lot of attention in things like spacecraft design, power line design, etc.
ALL structures are coupled resonators of some sort, and particularly
when there's an excitation to worry about (earthquakes, aeolian, road
vibrations), people pay a lot of attention.
IMO real understanding is beyond any rule of thumb, however I do like
the thin wall connected to thick wall reasoning. And building decent
models for analysis would be exceeding difficult to get all of the
reality captured correctly.
Yes and no - a *good* model is difficult, especially with a complex
structure (anything other than a single beam of uniform properties). -
An *ok* model might be enough to tell you you have a potential problem.
There are tools out there no more complex to use than NEC which can
handle this. I don't know if they're free, and just like NEC, there is a
learning curve with a fairly tall first step - just because you need to
know a fair amount of mechanical engineering terminology. (which, for
various reasons uses different symbols and definitions than electrical
engineering terminology)
BTW, a well known aeolian vortex killer is the spiral rope/tube wrapped
around the *outside* of the element.
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