David G. Nagel wrote:
wrote:
David G. Nagel wrote:
The last time that I built an antenna I used the formula to get the
appropriate length then I had to adjust it to obtain the optimal
readings for the frequency I was using.
Did "the formula" take into account any insulation, conductor
resistivity,
conductor diameter, height above ground, characteristics of the ground,
and objects in the near field including supports?
If not, what is your point?
The point is that those items are not part of "Antenna Theory: The
Science" but are a large part of "Antenna theory: The Art". . .
I disagree. Antenna operation (or "theory") is dictated by science. How
the mentioned factors affect antenna performance can all be calculated
from well established, known scientific principles -- no "art" is required.
However, there are some ways where art does get into the picture.
Practical antenna design usually requires tradeoffs, and there isn't
necessarily one optimum solution. Weighing the tradeoffs, often
including cost and time, requires knowledge and skill, and is a creative
process that could properly be described as art -- although the more
science you know, the bigger the bag of tricks you'll have for your
"art" project. And there are often factors which, although completely
deterministic in principle, aren't well enough known or are too complex
to practically include in calculations. There, the skill or "art" comes
in having a sufficient knowledge of the likely effects of those factors
to choose or adjust the design accordingly.
What a lot of people call the "art" of antenna design is just a
substitute for understanding. If you don't understand the underlying
science or how to apply it, the only tool you have is Kentucky windage
and guesswork, often called "art" as opposed to real understanding.
While people can very often arrive at a usable solution by using nearly
all "art" and little "science", they have more and better solutions to
choose from as they replace some of that "art" with "science".
Roy Lewallen, W7EL