UPDATE The new rule giving FM and LPFM stations an easier method of verifying directional FM performance has gone into effect. The FCC approved the change in May.
Several antenna manufacturers — Dielectric, Jampro, Radio Frequency Systems and Shively Labs, plus broadcaster Educational Media Foundation — sought the update, saying it would save station owners time and money, Inside Towers reported.
The change gives an FM and LPFM license applicant that uses a directional antenna the option of submitting computer generated proofs of the antenna pattern prepared by the manufacturer, in lieu of measured pattern plots and tabulations. The FCC already allows such computer modeling verification for AM and DTV directional antennas. The Commission expects the change will give applicants more flexibility in antenna siting, and reduce antenna and station construction costs.
The first time computer modeling is used for a particular antenna model, the station must submit both the results of the computer modeling and the measurements of either a full-size or scale model of the antenna or elements. This is needed to demonstrate “a reasonable correlation between the measurements achieved and the computer model results,” notes the Commission in a Federal Register notice. Once that antenna model or series of elements has been verified, subsequent applicants using the same model number or elements and the same modeling software may cross reference the original submission by providing the application file number, says the agency.
By Leslie Stimson, Inside Towers Washington Bureau Chief
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