RF Safety and Regulatory Spectrum Regulation Informational

What are the power and spurious emission limits for operation in the 60 GHz unlicensed band?

The 60 GHz unlicensed band spans 57-71 GHz in the US (FCC Part 15.255) and 57-66 GHz in the EU (ETSI EN 302 567). FCC Part 15.255 power limits: maximum average EIRP of 40 dBm (10W) with antenna gain up to 15 dBi, or 82 dBm minus 2 times the antenna gain dBi for high-gain antennas (e.g., 30 dBi antenna allows 22 dBm average transmitter power, 52 dBm EIRP). Maximum peak EIRP: 40 dBm for modulated signals. For fixed point-to-point links with antennas of gain ≥ 30 dBi: average transmit power up to 500 mW and no EIRP limit (allowing high-gain antennas for multi-kilometer links). Spurious emission limits: -13 dBm/MHz outside the 57-71 GHz band, and -9 dBm within any 100 kHz in the 57-71 GHz band outside the occupied bandwidth. ETSI EN 302 567 limits are more restrictive: maximum EIRP of 40 dBm (same) but with additional spectral density limits of 13 dBm/MHz maximum, and a specific spectral mask for out-of-band emissions. The 60 GHz band is unique because oxygen absorption creates natural isolation: atmospheric attenuation of 10-15 dB/km at 60 GHz limits interference range, making high EIRP feasible without causing harmful interference over distance. This band supports WiGig (802.11ad/ay) with channel bandwidths of 2.16 GHz and data rates exceeding 7 Gbps.

Category: RF Safety and Regulatory

Updated: April 2026

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60 GHz Unlicensed Band Regulations

The 57-71 GHz band is the largest contiguous unlicensed allocation in the US, providing 14 GHz of bandwidth. This massive spectrum resource enables ultra-high-throughput short-range communications, wireless backhaul, and emerging sensing applications.

Channelization and Applications

IEEE 802.11ad defines four channels of 2.16 GHz bandwidth each, centered at 58.32, 60.48, 62.64, and 64.80 GHz. 802.11ay extends to channel bonding (up to 4 channels = 8.64 GHz) for peak data rates exceeding 40 Gbps. Applications: (1) WiGig: short-range ultra-high-speed wireless (replacing HDMI cables, wireless docking stations, VR displays). Range: 1-10 meters. (2) Fixed wireless access (FWA): 60 GHz point-to-point and point-to-multipoint for ISP "last mile" deployment. Range: 100-500 meters (limited by oxygen absorption). (3) 5G backhaul: connecting small cells to fiber access points using 60 GHz links. (4) Radar/sensing: gesture recognition, presence detection, and short-range imaging (high bandwidth enables millimeter-range resolution). Typical chipset implementations: Qualcomm QCA6421, Qualcomm QCA6432 (WiGig), Peraso X720 (FWA), SiBeam SB6212 (streaming).

Propagation at 60 GHz

The 60 GHz band has unique propagation characteristics: (1) Oxygen absorption: O2 molecular resonance at 60 GHz causes 10-15 dB/km additional attenuation in dry air, peaking at about 60 GHz and decreasing rapidly above and below. At 62 GHz, rain attenuation adds 5-20 dB/km (for 25-100 mm/hr rain rates). (2) Free-space path loss: FSPL at 60 GHz is 68 dB at 1 meter (vs 40 dB at 2e4 GHz), making high-gain antennas essential. (3) Material penetration: 60 GHz signals do not penetrate walls, windows (low-e glass attenuates 30-40 dB), or foliage. Most indoor communication requires line-of-sight or single-bounce reflection. (4) Antenna size: a 30 dBi antenna at 60 GHz is only 2-3 cm in diameter, enabling high-gain pencil beams from small packages. Phased array antennas with 16-64 elements are common at 60 GHz, providing beam steering for mobile-to-fixed links.

Regulatory Comparison US vs EU

US (FCC Part 15.255): 57-71 GHz, maximum 40 dBm EIRP, higher power for fixed P2P. Relatively permissive, enabling longer-range outdoor links. EU (ETSI EN 302 567): 57-66 GHz (5 GHz less bandwidth), 40 dBm EIRP for broadband, but data throughput-dependent EIRP limits for specific device categories. Japan (MIC): 57-66 GHz, maximum 10W EIRP. South Korea: 57-66 GHz, generally following ETSI limits. China: 59-64 GHz, maximum 27 dBm EIRP (much more restrictive). Designing a globally certified 60 GHz product requires hardware support for the full 57-71 GHz range with firmware-configurable frequency and power limits for each jurisdiction. The antenna array design must support switchable radiation patterns to meet different EIRP limits while maintaining link performance.

Common Questions

Frequently Asked Questions

Why does 60 GHz not cause interference over long distances?

Oxygen absorption at 60 GHz creates a natural isolation barrier. At 15 dB/km absorption (on top of free-space path loss), a signal transmitted at 40 dBm EIRP at 60 GHz reaches the noise floor within 1-2 km. This means 60 GHz devices in different buildings or neighborhoods cannot interfere with each other, even with no coordination. This self-isolating property is why regulators allow relatively high EIRP (10W) in this band, compared to much lower limits at 5 GHz (4W) and 2.4 GHz (0.1W EU) where signals propagate much further. The oxygen absorption also provides inherent security: 60 GHz communications are extremely difficult to intercept or jam from a distance.

Can 60 GHz work outdoors?

Yes, for short-to-medium range links. Point-to-point 60 GHz links operate reliably at 100-500 meters for fixed wireless access and backhaul. Beyond 500 meters, oxygen absorption and rain fade reduce availability below commercial requirements (99.99%). For links beyond 500 meters, the 57 GHz and 64-71 GHz portions of the band have lower oxygen absorption (5-7 dB/km instead of 15 dB/km at 60 GHz) and are preferred. Link budgets for outdoor 60 GHz: 40 dBm EIRP + 40 dBi Rx antenna (2.5 cm dish) - 68 dB FSPL at 1m - 20log(R/1m) - 15×R/1000 dB O2 absorption. At 300m: 26 dB margin above -70 dBm sensitivity.

What antenna gain is needed at 60 GHz?

Minimum gain depends on range and application: indoor WiGig (<10m): 6-15 dBi (sector or moderate-gain horn). Indoor backhaul (10-50m): 15-25 dBi (small array or lens antenna). Outdoor P2P (100-500m): 30-43 dBi (parabolic dish or phased array). The small wavelength (5mm) means very small antennas achieve high gain: a 10 cm × 10 cm planar phased array with 256 elements achieves approximately 30 dBi gain with electronic beam steering. A 25 cm Cassegrain dish achieves 43 dBi at 60 GHz. Most consumer devices use substrate-integrated phased arrays (4×4 to 8×8 elements, 15-20 dBi) manufactured directly on the PCB or in the antenna-in-package (AiP) module.

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