[BC] FCC Approves proposed AM MoM Rules

[Phil Alexander]

On 26 Sep 2008 at 9:19, Craig Healy wrote:

> 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.

> 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.

> 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 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.


---------------------------------------------
Phil Alexander, CSRE, AMD
Broadcast Engineering Services and Technology 
(a Div. of Advanced Parts Corporation) 
Ph. (317) 335-2065   FAX (317) 335-9037