An FCC Commissioner is pushing the agency to create a new FM allocation. If the change happens, it could have implications for station towers.
Speaking at the Radio Show last week, Commissioner Ajit Pai said the creation of a new class of FM station, “C4,” is worth considering. Class C4 stations would have more power than Class ‘A’s but less than Class ‘C3’s. Specifically, C4-Fs would be allowed a maximum ERP of 12,000 watts from a reference antenna height of 100 meters above average terrain, he said.
If approved, “hundreds” of Class A FMs could likely upgrade to the new class, transmitting increased power and providing service to more potential listeners as long as the stations wouldn’t impact the existing service contours of other stations.
A broadcaster proposed the idea some two years ago and the feedback was positive from rural areas, according to Pai. The owner of KVPI-FM in Ville Platte, LA said the proposal would mean his station’s Cajun French and local music programming “would reach a larger area of South Central Louisiana.” The Multicultural Media, Telecom and Internet Council (MMTC) says the change would help small and minority-owned stations increase their coverage and gain access to capital.
Pai wants his colleagues to issue a Notice of Proposed Rulemaking on C4, so commissioners can seek public input and conduct a thorough vetting of the concept; that way, the agency would be in a better position to decide whether to implement the change.
Getting to the technical nuts and bolts of the concept, Class A stations have reference antenna heights of 100 meters above average terrain (with a 6 kW maximum for ERP). Under the current proposal, the C4 stations would retain the 100 meter antenna height, but a new transmitter and/or antenna would be needed, according to Cavell Mertz & Associates President Gary Cavell. A change in transmission line might also be required, depending on the particulars of the situation.
Asked by Inside Towers whether the change may have tower implications, he replied, “More towers are possible because the existing station-to-station spacing tables would be different for this new class, meaning that owners may have to relocate to meet the new station separation requirements that would be adopted.”
Cavell tells us: “Even if the station fortuitously didn’t need to move, the change in ERP would require a transmitter or antenna change, or both… and any change in antenna (more bays) means renting more space on the tower because the antenna would be longer – further, an extension in the height of the tower might be needed (if the antenna is right at the top) if the station wanted to keep the same radiation center height.”
Or, he adds “a station might want to trade more antenna height for a compensating reduction in power (per FCC Rule 73.211(b)(2) to keep the station’s “reference contour” within the class guidelines.”
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