Topband: Elevated Radials

[Tom W8JI]

> 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