[BC] FCC Approves proposed AM MoM Rules

[Craig Healy]

> > It must be rather difficult to create the cell tower model.
> > The antenna and line top load effect could be very complicated.
>
> It is more tedious than complicated. VERY tedious if the cell
> is on a self-supporter like a Rohn because these must be modeled
> as the full geometric lattice while for uniform cross-sectional
> guyed towers and poles a simple cylinder or tapered cylinder
> is a suitable substitute.

And if every line and antenna is connected correctly...  It may be tedious,
but I'd also have to question how the accuracy could be verified.  However,
it's not a deal breaker, I suppose.

> > If the tower has a detuning
> > network in place that also can affect things significantly.
>
> Not really. The first approximation is with no detuning to see
> the maximum extent of the problem, and then you can suppress it
> by reducing the current flow to near zero - actually by an analog
> of the near field reduction of the detune.

When stations are close in proximity, then the detuning network might not be
for that same station.  I can think of a couple of places in the
Boston-Providence area where a given cell structure can affect more than one
station.  Brockton, MA 1410/1460 and Providence, RI 630/920 are a couple of
examples that come to mind.

> > Again, I probably am not clear on this but I don't see how any
> > existing software could begin to accurately model real life.
>
> How do you suppose they design stealth aircraft and stealth ships
> which we do have although they may not be quite as stealthy as a
> stealth bomber.

I would think through modeling as well as computer design.  I know someone
who is in the military who may well be able to provide a rough answer to
that question.  I seriously doubt it's just theory and not physical testing,
and lots of it.

Given the huge numbers of things that can affect a pattern, plus wildly
variable ground conductivity, I dodn't think I have a lot of faith in a
software end-all solution.  If I were to see a number of designs done both
in the traditional and computer-generated way, then it would clarify things.

> > I remember a fellow
> > around here who designed a lot of arrays, and many could never
> > really meet the paper design results.
>
> Other than environment issues (a/k/a re-rad structures and power
> lines) plus the inability of some to understand the idea of field
> measurement point quality, i.e. ratio of direct vs. re-rad wave,
> there is no real reason for this because most of these issues can
> be resolved except for dense power lines which is a major reason
> for the new rule.

Don't get me wrong, if this actually works - and can be PROVEN - then I'm
all for it.  I just would want some hard evidence that it's as good as is
hoped.

Craig Healy
Providence, RI