A year ago, the FCC approved the use of a computer modeling technique, known as "moment method modeling", to allow certain AM stations to do Proofs of Performance of directional antenna patterns without the costly and time-consuming process of proofing the antenna performance through the use of actual field strength measurements. Last week, the FCC issued a Public Notice clarifying the process for the use of this process. The Commission notes that these guidelines are issued based on the staff’s current interpretation of the rules, that the notice is not intended to be precedential and to bind the Commission, and that these issues will be addressed by the staff in more detail as specific cases arise.
The Public Notice addresses subject such as:
- Types of Antenna Systems Eligible: Only antennas with series-fed radiators can use this method – not those with folded unipoles or sectionalized antennas
- Tower Location Tolerance: Noting that the a surveyor must certify that the antenna has been properly located and each tower is properly oriented, with a tolerance of 1.5 electrical degrees for each tower in the array
- Antenna Monitor Calibration: Reliance on the technique requires a certification that the antenna monitor has been properly calibrated in accordance with manufacturer’s specifications
- Filing Fees: Applicants must pay the license fee and directional antenna fee for both licenses to cover construction permits or to support a new license without monitoring points.
- Specific information for accounting for base region effects when base sampling is used, agreement between calculated and measured tower base impedances, the requirement to measure impedance of sampling line with sampling device connected, and the determination of licensed parameters vs. operating tolerances is also provided
More specific information can be found in the Commission’s Public Notice.