Band n260 (39 GHz)
Understanding Band n260
Band n260 occupies the 37 to 40 GHz range, sitting above the n257 and n258 bands. This frequency range was previously used for LMDS (Local Multipoint Distribution Service) fixed wireless and point-to-point microwave links. The FCC re-allocated it for 5G mobile use, selling 3 GHz of spectrum in 100 MHz blocks across the country. The band provides the same 400 MHz maximum channel bandwidth as the 28 GHz bands, enabling identical peak data rates, but at shorter range due to the higher frequency.
The physics at 39 GHz are incrementally more challenging than at 28 GHz. Free-space path loss is 2.9 dB higher (20 log(39/28)). Rain attenuation increases from approximately 7 dB/km at 28 GHz to approximately 10 dB/km at 39 GHz for moderate rain. However, the shorter wavelength means antenna elements are 28% smaller in each dimension, so the same physical aperture size can support 1.9 times as many elements. A 1024-element array at 39 GHz fits in roughly the same space as a 512-element array at 28 GHz, providing 3 dB more array gain. This nearly compensates for the additional path loss, making 39 GHz viable for the same deployment scenarios.
Band n260 vs. 28 GHz Bands
ΔFSPL = 20 log(39/28) = 2.88 dB additional loss at 39 GHz
Antenna Element Size:
λ/2 at 28 GHz = 5.36 mm
λ/2 at 39 GHz = 3.85 mm
Area ratio: (5.36/3.85)² = 1.94× (nearly 2× elements per area)
Array Gain Compensation:
1024 elements at 39 GHz ≈ same size as 512 at 28 GHz
ΔG = 10 log(1024/512) = 3.01 dB (compensates path loss)
Rain Attenuation (moderate rain, 25 mm/hr):
28 GHz: ~7 dB/km | 39 GHz: ~10 dB/km
mmWave Band Deployment Status (US)
| Band | Frequency | FCC Auction | Major License Holders | Deployment Status |
|---|---|---|---|---|
| n261 (28 GHz) | 27.5-28.35 GHz | Auction 101 (2019) | Verizon, AT&T, T-Mobile | Active (urban) |
| n260 (39 GHz) | 37-40 GHz | Auction 103 (2020) | T-Mobile, Dish, US Cellular | Active (dense urban) |
| n262 (47 GHz) | 47.2-48.2 GHz | Auction 103 (2020) | Various | Limited trials |
Frequently Asked Questions
How does 39 GHz compare to 28 GHz for 5G deployment?
Path loss at 39 GHz is 2.9 dB higher than at 28 GHz, and rain attenuation is approximately 50% worse. However, the shorter wavelength allows roughly twice as many antenna elements in the same physical area, providing ~3 dB more array gain. In practice, 39 GHz cells have slightly shorter range but comparable throughput in a more compact antenna form factor. The two bands are complementary: 28 GHz for broader coverage and 39 GHz for maximum density.
What was the FCC 39 GHz spectrum auction?
Auction 103 (Dec 2019 to Mar 2020) combined 37 GHz, 39 GHz, and 47 GHz spectrum into the largest-ever spectrum auction, raising $7.56 billion. The 37 to 40 GHz range was sold in 100 MHz blocks across 416 Partial Economic Areas. Major winners included T-Mobile (inheriting Sprint's 39 GHz holdings), Dish Network, and regional carriers. The spectrum was previously used for LMDS and fixed service links.
What antenna configurations support 39 GHz operation?
Base stations use 512 to 1024 element arrays providing 27 to 30 dBi per beam. Element spacing of 3.85 mm (λ/2) means a 1024-element 32×32 array measures only ~124 mm square (~5 inches). User equipment uses 4 to 8 elements in smartphones and 16 to 64 elements in fixed wireless CPE. Multiple antenna panels on different device faces support beam switching for NLOS coverage.