71.0 GHz Band
Understanding the 71.0 GHz Band (E-Band)
When you cross the 71.0 GHz threshold, you leave the globally unlicensed, oxygen-choked V-Band (WiGig) and enter the highly regulated, high-capacity realm of the E-Band.
The E-Band is the telecom industry's ultimate weapon for 5G backhaul.
The Atmospheric Window
The laws of physics dictate that the 60 GHz band is completely absorbed by oxygen, causing the signal to die within a few hundred feet.
However, at exactly 71.0 GHz, the oxygen absorption abruptly stops. This creates a massive, clear 'Propagation Window' in the atmosphere. A 71 GHz radio wave can travel straight through the oxygen unimpeded, allowing engineers to shoot a massive, laser-like millimeter-wave beam up to 2 to 3 miles between two skyscraper rooftops.
The Massive Channel Sizes
The primary reason telecom carriers love the 71.0 GHz band is the sheer, astronomical amount of empty spectrum available. The lower E-Band provides a contiguous block of 5,000 MHz of spectrum (71 GHz to 76 GHz).
- A traditional 7 GHz microwave link might use a tiny 56 MHz channel to push 1 Gigabit.
- A 71.0 GHz E-Band link can easily utilize massive 500 MHz, 1000 MHz, or even 2000 MHz channels.
- By using highly focused 1-foot parabolic dishes and massive channels, a single E-Band link can effortlessly blast 10 to 20 Gigabits per second across a city, perfectly mimicking the speed of an underground fiber-optic cable without the massive cost of digging up the street.
Key Equations
The 71.0 GHz Band is a massive, strictly licensed millimeter-wave spectrum block that marks the absolute lower boundary of the highly strategic E-Band (spanning 71-76...
Key specifications:
71.0 GHz | -76 GHz | -86 GHz | 60 GHz | 71 GHz | 3 m
Power: P(dBm) = 10log(PmW), 0dBm = 1mW
Comparison
| Band | Range | Wavelength | Application | Standard |
|---|---|---|---|---|
| 71.0 GHz Band | 71 GHz region | 4.2 mm | Primary use | ITU allocation |
| Adjacent lower | 63.9 GHz | 4.7 mm | Related band | Shared spectrum |
| Adjacent upper | 78.1 GHz | 3.8 mm | Related band | Guard band |
| Harmonic 2f | 142.0 GHz | 2.1 mm | Spurious | Filter required |
| Sub-harmonic | 35.5 GHz | 8.5 mm | LO option | Mixer design |
Frequently Asked Questions
Does rain affect the 71 GHz band?
Violently. While 71 GHz completely ignores oxygen, it is completely defenseless against water. The 4-millimeter radio wave is roughly the exact size of a massive raindrop. During a torrential downpour, the rain violently scatters the beam (Rain Fade). If an engineer tries to build a 71 GHz link longer than 3 miles, the link will absolutely crash during a heavy storm.
Is the 71 GHz band licensed?
Yes, but it uses a unique 'Light Licensing' model in many countries (like the US). Because the E-Band beam is incredibly narrow (like a laser), it is almost impossible for two dishes to accidentally jam each other. An operator can instantly register their exact GPS coordinates in an automated database, pay a tiny fee, and launch the link immediately, drastically speeding up 5G network deployment.
How does FDD work in the E-Band?
The E-Band is split into two massive chunks. A cell tower will use the 71-76 GHz block strictly to Transmit (Download), and it will use the mathematically distant 81-86 GHz block strictly to Receive (Upload). This Frequency Division Duplexing (FDD) allows the multi-gigabit laser beams to operate simultaneously at full speed without blinding their own receivers.