D-Band

Radio transmits data using electromagnetic waves that oscillate at different rates per second. This oscillation rate is called frequency and is measured in hertz. Radio, WiFi, and mobile networks each use their own ranges so they don’t interfere with each other. The D-Band is one such range, and a very high one at that: the waves there oscillate 110 to 170 billion times per second. For comparison: mobile networks today typically operate at under four billion oscillations per second. The D-Band therefore sits roughly forty times higher than what a normal smartphone uses.

Why such high frequencies are being sought in the first place

In the low ranges, things have gotten crowded. Mobile networks, television, satellites, government radio, and WiFi all share the available frequencies there. New services can barely be allocated contiguous blocks anymore. However, how much data a radio link can handle depends heavily on how wide that block is.

And this is exactly where the appeal of the D-Band lies. It spans 60 gigahertz of bandwidth in one contiguous piece. That’s more room than all of classic mobile networking below six gigahertz combined offers. This makes transmission rates of several hundred gigabits per second conceivable. A high-resolution feature film could be transmitted in a fraction of a second.

For the AI industry, this is no side issue. Data centers need to move huge amounts of data between servers and locations. Fiber optics is ideal for this, but laying it takes months and costs a lot. A radio link in the D-Band can be set up in days and achieves similar magnitudes.

Short waves, short range

High frequency means short wavelength. In the D-Band, a wave is only about two millimeters long. Such waves behave almost like light: they travel in straight lines and are stopped by obstacles. A house wall, a tree, or even just a hand is enough to break the connection.

On top of that comes attenuation from the air itself. Oxygen and water molecules absorb part of the energy. In heavy rain, a link can therefore collapse. In practice, usable ranges are usually only a few hundred meters to a few kilometers, and that requires a direct line of sight.

Technically, this is addressed with highly focused antennas. Instead of transmitting in all directions, a narrow beam is aimed precisely at the receiver, similar to a searchlight. This method is called beamforming. Because the waves are so short, hundreds of antenna elements fit onto an area of just a few square centimeters. Incidentally, a common misconception is that D-Band radiation is especially dangerous. It barely penetrates the skin, because it is already absorbed at the surface.

From the lab to a mobile network standard

In everyday life, you won’t encounter the D-Band yet. No smartphone supports it, and even the current 5G network doesn’t use it. Where it is already in use, it’s invisible: as a microwave backhaul link between mobile network towers, establishing the connection to the core network where no fiber optic cable is laid.

In trade news, the term mainly comes up in connection with 6G. That’s the planned next mobile network generation, expected to arrive around 2030. Companies like Nokia, Ericsson, and Samsung regularly showcase record-breaking trials using D-Band technology. The World Radiocommunication Conference, where countries coordinate the international use of frequencies, has already earmarked parts of the band for mobile use.

You shouldn’t confuse the D-Band with so-called mmWave 5G, which operates at 24 to 40 gigahertz. Experience with that has been sobering: in the US, the cells are so small that widespread rollout is hardly worthwhile. In the D-Band, the cells would be even significantly smaller. Realistically, it is therefore not a replacement for normal mobile networking, but a supplement in places with very high data demand, such as stadiums, factory halls, or train stations.