After exploring the various orbits on which satellites are placed, we’re now diving into the different frequency bands they use. Let’s first review how the radio spectrum is laid out (open it full screen for a better view).

I’ve added a few usage examples to help you get your bearings. To meet more specific engineering needs, sub-bands have been introduced that are widely used for satellite communications. It’s these sub-bands that we’re gonna focus on in this lesson.

Here’s how these well-known bands are organized, ranging from UHF to EHF.

The L band ranges from 1GHZ to 2GHz in the UHF spectrum. It’s widely used for satellite positioning systems like GNSS, such as the famous American GPS or the European Galileo. You’ll also find weather satellites like NOAA, METEOR, GOES and many more! Yep, NOAA and METEOR also broadcast in VHF at 137MHz, among other data types. These waves have the advantage of being highly resistant to weather conditions like rain, but they aren’t built to carry huge amounts of data due to their low bandwidth.

The S band stretches from 2GHZ to 4GHz, straddling both UHF and SHF. You’ll again find weather satellites like NOAA and also the DMSP (Defense Meteorological Satellite Program). There are solar observation satellites like Hinode (Solar-B). Plus, it handles audio communications with the International Space Station (ISS). In short, while this band is also resilient against bad weather, it’s best suited for communications that don’t demand high bandwidth.

The C band covers 4GHZ to 8GHz in the SHF range. It’s hugely popular for satellite TV, especially in rainy climates. Think of the first telecom satellite Early Bird by Intelsat or some of the older Hot Bird satellites from Eutelsat that use it. These satellites are often placed in geostationary orbit to cover vast areas. Although the C band offers decent bandwidth, it requires pretty big satellite dishes (2/3m) for TV reception. Plus, it’s getting more congested worldwide, pushing companies to move to higher frequency bands. Also, this band is affected by 5G network interference around 3.5GHz.

The X band spans from 8GHZ to 12GHz, also within the SHF range. Widely used by militaries around the globe, like French Syracuse satellites or American WGS, its high bandwidth allows for high-resolution image transmission along with encrypted communications. However, weather conditions start to impact it, forcing satellites into lower orbits which reduces their coverage.

The Ku band (Kurz-under, with K for Kurz meaning short in German, and u for under) runs from 12GHZ to 18GHz in the SHF band. Super popular, it’s the go-to for satellite TV, gradually replacing the C band. In fact, this band can transmit more data with much smaller satellite dishes (60cm/1m). Although rain affects it, advances like robust modulation techniques and automatic correction systems help minimize signal loss. You’ll find satellites such as Hot Bird and EuroBird from Eutelsat or even Galaxy from Intelsat. It also handles audio, video, and data communications with the ISS, unlike the S Band which is used only for audio. Starlink also makes use of part of this band for uplink and downlink between the satellite and the user’s antenna (terminal).

The K band ranges from 18GHZ to 27GHz, the last of the SHF frequencies. At 22.235GHz, water vapor molecules in the atmosphere hit their natural resonance, meaning they absorb electromagnetic waves effectively at that frequency, causing signal attenuation. We won’t get into the chemical details, but this band isn’t designed for long-range communications because of that critical frequency. In short, it’s rarely used except for a few radars and radio telescopes. Also note the segments 17.80-18.60GHz and 18.80-19.30GHz that Starlink uses for communications between satellites and ground stations connecting the satellite network to the Internet (gateways).

Finally, we hit the EHF range with the Ka band (Kurz-above, meaning “above”), which runs from 27GHz to 40GHz (yeah, there’s still 3GHz left in SHF). Due to the very high frequencies, there’s significant weather-related attenuation, making it less ideal for rainy climates without advanced modulation techniques. However, it offers massive bandwidth, supporting bidirectional communications that can handle huge amounts of data with small satellite dishes. Plus, the Ka band packs more frequencies than the Ku band, meaning more capacity translates to more offers and lower prices. That’s why this band is a favorite for satellites providing Internet services akin to ADSL. You’ll see many of the usual players like Intelsat, Eutelsat, or Starlink using it for communications between satellites and gateways.

The V band spans from 40GHZ to 75GHz within the EHF range. It’s an experimental band that, despite breaking bandwidth records, is heavily impacted by atmospheric conditions. Starlink has started using it, but there are significant challenges to overcome before it’s fully viable. There’s also a WiFi standard known as WiGig that uses 60GHz, with a range of just 10m but a theoretical throughput of up to 6.75GHz! In short, there isn’t much to say about this band other than it might become really popular in the coming years.

And that’s it for this lesson loaded with info, the more you know about these bands, the better for dabbling in satellite radio hobbies. Just a quick note: despite their high frequencies, these waves aren’t dangerous to your health! They’re always in the realm of non-ionizing radiation and can’t alter your DNA 🧬.