42.0 GHz Band
Understanding the 42.0 GHz Band
As telecommunications networks run out of room in the lower microwave frequencies (like 11 GHz and 18 GHz), engineers are forced to push higher into the millimeter-wave spectrum. The 42.0 GHz Band sits in the lower portion of the V-Band, offering massive amounts of empty bandwidth.
The Physics of 7.1 Millimeters
At 42.0 GHz, the radio wave is so tiny (7.1 mm) that it behaves more like a laser beam than a traditional radio signal.
| The Feature | The 42 GHz Reality |
|---|---|
| Extreme Antenna Gain | Because the wavelength is microscopic, a small 1-foot parabolic dish can focus the 42 GHz energy into an incredibly tight, 1-degree 'pencil beam.' This ensures zero signal bleeds into the surrounding neighborhood, allowing engineers to install dozens of 42 GHz links in the same city without causing interference. |
| Severe Rain Fade | The fatal flaw of 42 GHz is water. Physical raindrops are larger than the radio wave. A heavy thunderstorm will violently absorb and scatter the beam. A 42 GHz microwave link is therefore strictly limited to "short-haul" connections, usually less than 2 miles long, to ensure the signal can survive a heavy downpour. |
The Regulatory Minefield
Unlike the heavily commercialized 39 GHz band used by Verizon for 5G, the 42 GHz band is heavily protected by international law.
Right next door to the 42 GHz band is a massive "Passive Zone" heavily utilized by Radio Astronomers to listen to the faint electromagnetic emissions of deep space and Earth's atmosphere. If telecom operators deploy massive amounts of 42 GHz equipment, the accidental 'out-of-band emissions' (the noise bleeding over the edge of the frequency channel) could blind these highly sensitive scientific instruments. Therefore, governments enforce massive power restrictions and strict filtering requirements on any equipment operating at 42 GHz.
Key Equations
The 42.0 GHz Band (encompassing the 40.5 to 43.5 GHz spectrum block) is an expansive segment of the V-Band allocated globally for ultra-high-capacity point-to-point microwave...
Key specifications:
42.0 GHz | 43.5 GHz | 7.1 m | 112 MHz | 250 MHz
Power: P(dBm) = 10log(PmW), 0dBm = 1mW
Comparison
| Band | Range | Wavelength | Application | Standard |
|---|---|---|---|---|
| 42.0 GHz Band | 42 GHz region | 7.1 mm | Primary use | ITU allocation |
| Adjacent lower | 37.8 GHz | 7.9 mm | Related band | Shared spectrum |
| Adjacent upper | 46.2 GHz | 6.5 mm | Related band | Guard band |
| Harmonic 2f | 84.0 GHz | 3.6 mm | Spurious | Filter required |
| Sub-harmonic | 21.0 GHz | 14.3 mm | LO option | Mixer design |
Frequently Asked Questions
Is 42 GHz used for 5G cell phones?
Not currently. The 3GPP has not officially defined standard commercial 5G NR bands operating in the 42 GHz range, focusing instead on the 28 GHz and 39 GHz bands. 42 GHz is primarily used for 'Backhaul'—the invisible microwave links that connect the actual cell tower back to the main fiber-optic internet backbone.
Do satellites use 42 GHz?
Yes. The ITU has allocated portions of the 42 GHz band for Fixed-Satellite Service (FSS) and Broadcast-Satellite Service (BSS). As lower satellite bands (like Ku-band and Ka-band) become completely congested, satellite operators are designing next-generation V-Band satellites capable of using 42 GHz to blast massive data streams down to dedicated ground stations.
What is the channel spacing in the 42 GHz band?
Because there is so much empty space, regulators allow massive channel sizes. While a low-frequency microwave link might only be given a 28 MHz channel, a 42 GHz link is often assigned massive 112 MHz or 250 MHz contiguous channels, allowing the radio to easily push 1 to 2 Gigabits per second.