Overview and Scope of 76-81 GHz Radar Service
The Federal Communications Commission issued a Small Entity Compliance Guide (DA 24-200) for the rules adopted in ET Docket No. 15-26 (FCC 17-94). The regulatory framework establishes a contiguous five-gigahertz band across 76-81 GHz for vehicular radars and airport air operations area radars by allocating 77.5-78 GHz to the Radiolocation Service on a primary basis alongside existing primary allocations at 76-77.5 GHz and 78-81 GHz.
Under 47 CFR Part 95, Subpart M, operators are licensed-by-rule, meaning individual station licenses are not required provided operations comply with service rules. Fixed radar use in the band is restricted exclusively to airport air operations areas where signals do not illuminate public roadways. Airborne operation of 76-81 GHz radars aboard aircraft or helicopters in flight is strictly prohibited.
- Applies to vehicular radars across various transportation platforms and airport air operations area radars such as foreign object debris (FOD) detection systems.
- Airborne use is prohibited to prevent interference with Radio Astronomy Service operations, requiring aircraft-mounted ground-use radars to incorporate automatic shut-off capabilities.
- Licensed-by-rule model affords collective interference protection based on primary allocation status without individual station license filings.
Technical Limits and Equipment Certification
Radar devices operating under Part 95 Subpart M must obtain equipment authorization certification in accordance with Part 2 Subpart J and Part 95 requirements. Modulation details and technical parameters must be submitted using FCC Form 731.
Radiated power limits under 47 CFR Section 95.3367 restrict fundamental emissions within the 76-81 GHz band to a maximum average EIRP of 50 dBm using a 1 MHz resolution bandwidth (RBW) integrated across the occupied bandwidth, and a maximum peak EIRP of 55 dBm in any 1 MHz RBW using a peak detector. Out-of-band emissions must consist entirely of spurious emissions compliant with 47 CFR Section 95.3379, and mobile and portable devices require radiofrequency exposure evaluation under 47 CFR Section 95.3385.
- Average EIRP limit: Maximum 50 dBm across the occupied bandwidth using 1 MHz RBW power averaging.
- Peak EIRP spectral density limit: Maximum 55 dBm/MHz measured with a positive peak detector and peak hold.
- FMCW power measurements do not require halting frequency sweeps, provided measurement instruments sweep across the full transmission range.
- Operations may be conducted under manual or automatic control pursuant to 47 CFR Section 95.3347.
Transition Periods and Grandfathering Rules
The Report and Order phased out vehicular radar operations in several legacy bands. References to vehicular radar use in the 16.2-17.7 GHz and 46.7-46.9 GHz bands were deleted from Part 15, with applications for equipment certification ceasing on July 13, 2017. Existing installed units are grandfathered for the life of the vehicle.
For the 24 GHz bands (22-29 GHz and 23.12-29 GHz), wideband and ultra-wideband (UWB) vehicular radar certifications ceased after September 20, 2018. Marketing, sale, importation, manufacture, and Class II permissive changes ended on January 1, 2022, with an exception allowing replacement sales from existing stock solely for the repair of pre-2022 installations when 76-81 GHz replacements are not viable.
- Part 15 narrowband radars operating under Sections 15.245 (24.075-24.175 GHz) and 15.249 (24.0-24.25 GHz) remain permitted and are not subject to the phase-out.
- Level Probing Radars under Section 15.256 operating in the 75-85 GHz range remain authorized on an unlicensed Part 15 basis.
- No new recordkeeping or reporting requirements were established by the Report and Order.