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Amateur Radio Poised to Retain Full 76-81 GHz Band, Sharing with Vehicular Radars


In a draft Report and Order (ET Docket No. 15-26) to be considered at its July 13 open meeting, the FCC is proposing to lift a nearly 2-decade-old suspension of Amateur Radio access to 76-77 GHz, giving the Amateur and Amateur-Satellite services access to the full 76-81 GHz band on a secondary basis. The FCC also reduced Amateur Radio’s status from primary to secondary in the 77-77.5 GHz segment, to match the rest of the 76-81 GHz band, and it imposed a uniform power-level limit for users of the band. The draft Report and Order (R&O) concludes that Amateur Radio and vehicular radars will be able to successfully share the millimeter-wave band with minor adjustments in the Amateur Service rules. A goal of the proceeding has been to expand and consolidate the spectrum available worldwide for 76-81 GHz radar operations. It brings the US Table of Allocations into line with decisions at the 2015 World Radiocommunication Conference (WRC-15) and makes the entire band available internationally for vehicular radars operating in the Radiolocation Service (RLS). The FCC said its proposal “received significant support” and no opposition from commenters regarding the proposed allocation.

The rule changes we adopt modifying the regulatory status of amateur stations and capping their power levels will ensure the continued operation of amateur stations in this band, and are a reasonable alternative to expanding the suspension of amateur operations from the 76-77 GHz band to the remainder of the 76-81 GHz band or removing the amateur allocations altogether from the 76-81 GHz band,” the draft R&O said. “In addition, these changes, coupled with the nature of amateur operations in the band (e.g., largely experimental, occurring temporarily on mountaintops and locations where motor vehicle operation is not typical, and using antennas mounted on masts as high as practical), will ensure that the potential for harmful interference from amateur operations to vehicular radar operations in the 76-81 GHz band is negligible and satisfy our efforts to ensure protection for the important safety functions that vehicular radars will provide.”

The FCC R&O would impose a 55 dBm peak effective isotropic radiated power (EIRP) limit (316 W EIRP) on Amateur operations in the band. This is the same as that allowed to vehicular radars. The R&O reasons that the risk for potential interference between Amateur Radio operation and RLS operations “is mitigated by the directionality of vehicular radars’ antennas — downward in orientation and mounted on a low position on the vehicles.” The R&O also cites the periodic and transient nature of amateur operations in the band coupled with high path losses in a band that is conducive to frequency re-use.

In reaching its tentative conclusions in the proceeding relative to the Amateur allocation, the FCC considered the comments of several individual radio amateurs as well as ARRL, Bosch, Delphi, the Automotive Safety Council, the Consumer Technology Association (CTA), and automakers and their representatives, among others. Several automotive manufacturers had asked that Amateur Radio be ousted from the band.



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