[BC] FCC Approves proposed AM MoM Rules

[dynotherm at earthlink.net]

While pattern b/w may be potentially improved using modeling tools,
alteration of AT LEAST operating parameters will be necessary, and
frequently radiator relocation/array reconfiguration will be the
main requirement.

The FCC engineering criteria in 73.160 thru 73.190 will be unchanged
thus pattern development using modeling alone is not feasible.
Pattern development remains a specialized discipline requiring
understanding of RF field interactions and experience. However,
modeling does permit simplification of proof of pattern performance,
essentially eliminating the need for radial H field measurements.
This may greatly facilitate the transition to IBOC AM which will
require pattern revisions and proving them.

Jerry Westberg's fine programs are directed at transmission system
design, not pattern design or proof of performance.

Finally, NEC-2 and NEC-4 based modeling programs are not free from
operator induced errors when structures are incorrectly modeled.
These programs have many pitfalls for the unwary. Thus, while the
approval of modeling to ease the array proof of performance can
be a great help it should not be seen as a panacea for cheap
correction of poorly designed arrays that probably should never
have been constructed 40 to 60 years ago.

Phil Alexander, CSRE, AMD



-----Original Message-----
>From: towers at mre.com
>
>Patten BW is not part of the MoM proceeding.  Increased pattern BW is a
>side benefit to the use of MoM.
>
>One uses software to model the array.  Jerry Westberg has a nifty program
>for doing this.  It's time consuming and is a bit quirky.  But it gets the
>job done AND does so with relative ease. His program also will show pattern
>BW and symetry.  Way cool. 
>
>Between NEC4 and Jerry's program's, the reality of doing one's own patterns
>is obtainable...though not practical if you are not well versed with ALL
>aspects of pattern design.  There are still MANY factors which one needs to
>consider that are not in those two programs before MoM is a viable tool.