I've noted your postings re elevated radials to replace deteriorated
buried
radial fields under broadcast towers. I'm familiar with the work and the
results. This work, of course was done by professional broadcast engineers
with significant instrumentation at their disposal. Of course, they also
had
to measure the field intensity in the far field and file it with the FCC.
Their work seemed to show that, once we have installed 4 elevated 1/4 wave
radials we're reaching the point of "diminishing returns" and that little
is
to be gained by increasing the number of radials beyond 4.
Charlie,
We shouldn't be critical of people. People believe what they want to
believe, including you and all of us. Here is how it really works:
1.) In an FCC measurement, a test signal is sent and the SLOPE of
attenuation in the far field is used to estimate earth conductivity.
2.) A graph (or formula, but generally a graph) based on the measured
attenuation slope is used to predict the expected signal at standard
distances.
This creates a problem, because if we look at measurements along a line in
any direction, they are often all over the place at various points. The
engineer has to smooth the readings out and match a curve, which gives the
engineer considerable lattitude depending on how he does the smoothing.
Even more important, ONE measurement system over one ground that contains
multiple old radials of unknown condition and one set of soil conditions
does not mean it applies to other conditions.
By far, the most accurate way to determine a change is to do a direct
measurement of what we want to know in an A-B comparison with only the
variable we are trying to define changed. This takes out the human emotional
factors and other errors, and then rememmber it applies to that case.
No matter how much we want something to be true, or how much we like or
agree with something, this is just how it **really** works. It's human
nature to gravitate toward a system that takes little room and installation
time, doesn't cost much, and is an "it always works this way" silver bullet.
We should not pick at people and call people names who point out obvious
flaws and limitations in faith-based conclusions. Anyone who has objectively
made measurements realizes there is no single universal answer, no matter
how nice it would be if there actually was one.
73 Tom
_________________
Topband Reflector
|