Looking over that proposed rule..
"(c) Proponents of construction or significant modification of a tower
within the distances defined in (a) and (b) herein of an AM station
shall examine the potential effects thereof using a moment method
analysis. The moment method analysis shall consist of a model of the AM
antenna together with the potential reradiating tower in a lossless
environment. The model shall employ a simplified version of the
methodology specified in § 73.151(c) of this chapter. The AM antenna
elements may be modeled as a Federal Communications Commission FCC
08-228 series of thin wires driven to produce the required radiation
pattern, without any requirement for measurement of tower impedances."
This seems pretty straightforward, but I don't know anything about the
"simplified version of the methodology in 73.151(c)"
Anyone have a "25 words or less" summary of what this kind of model is?
Each tower modeled as a single wire of appropriate diameter, and driven
with a current source of the appropriate phase?
And when they say lossless environment, does that mean "perfect ground"?
There is, or used to be, a nifty site that had all the antenna info for
broadcast stations, at some level of detail (physical and electrical
height of radiators, phasing, physical positions), and it would
conceivably be pretty easy to make a script that would extract this and
generate the required NEC deck for a ham to use. (or, for all we know,
the stations already have the NEC model in their application)
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