There still seems to be some confusion regarding computer modeling rules for AM directional antenna performance verification, despite the Federal Communications Commission's attempt to clarify the procedures this fall.
That is the word from an AM broadcast engineering source who wants to help un-muddy the waters.
The Media Bureau said in its Oct. 29 Notice that it has received lots of inquiries about new rules that explain requirements for moment method proof of performance, which are optional for eligible AMs.
The FCC permits stations to use moment method modeling only for directional antenna arrays consisting of series-fed radiators. Directional antennas with top-loaded elements are eligible for moment method modeling, provided the towers are fed in series. Folded unipoles and sectionalized antennas are not eligible.
In addition, directional antennas using the new proof techniques must have standard ground systems. DAs with non-standard ground systems must continue to use the proof of performance rules based on field strength measurements.
My engineer says stations filing a Form 302 license application and who want to use moment method modeling don't need to file a site survey. He says while a few stations are in fact filing the forms at the commission, he senses more who could do so are not, missing out on an opportunity to save money. The total cost for a MoM application is $8,000 to $10,000, considerably less than a conventional partial proof.
Stations that have been operating on STAs may want to consider licensing under the new rules as a cost-effective solution to fixing array problems.