There’s a strange beauty in the way satellites communicate. No wires, no internet cables—just invisible waves passing through space. These signals travel across oceans and continents, carrying important information like satellite health, position, and sometimes even voices.
For small satellites like PocketQubes—tiny spacecraft that can fit in your hand—the most common way to send and receive signals is through UHF (Ultra High Frequency) and VHF (Very High Frequency). They’re not as fast as fiber internet, and they’re not the newest technology. But they are simple, reliable, and—when used well—surprisingly effective.”
These radio signals can help us earthlings stay connected with a small spacecraft orbiting hundreds of kilometers above Earth. Sometimes, all we need is a ground antenna, a receiver, and just the right timing as the satellite passes overhead.
Of course, using these radio frequencies for satellite communication usually requires a proper license, depending on national regulations. But the good news is: many countries support educational and amateur radio projects, making it accessible to students, hobbyists, and small teams around the world.
So why are these quiet radio waves still so important? Let’s take a closer look.
What Are UHF and VHF?
Let’s start with the basics. Think of radio frequencies like different lanes on a highway—each lane carries a certain kind of traffic.
VHF, or Very High Frequency, is one of the lower lanes, running from about 30 to 300 MHz. It’s been around for a long time and is used in things you might know, like FM radio stations, communication on ships, and early satellite signals that help us track satellites in space.
Just above VHF is UHF, or Ultra High Frequency, which covers from 300 MHz up to 3 GHz. You can find UHF in TV broadcasts, mobile phones, GPS devices, and many satellites sending back detailed information.
For small satellites, these two frequency bands each have their own special roles:
- VHF is like the satellite’s “beacon light” — it sends out simple signals that tell us it’s alive and share basic information.
- UHF is more like a two-way walkie-talkie, allowing the satellite to both send data and receive commands from Earth.
What makes these bands great for small satellites is that they don’t need big or complicated antennas to work well. Plus, many amateur radio enthusiasts around the world use these same frequencies, creating a helpful community that supports satellite communications.
Why Small Satellites Use Them
Let’s be honest—small satellites don’t have much space inside. Imagine trying to fit all the tools you need into a tiny backpack. That’s what engineers face with antenna size, power supply, and the weight of all the parts.
This is where VHF and UHF come in—they’re like the perfect-sized tools that fit just right. Because their radio waves are longer, they let satellites use:
- Simpler antennas, like little sticks or foldable “whips” that don’t take up much room.
- Less power, so the satellite’s battery doesn’t run out quickly.
- Wider coverage, meaning the satellite doesn’t have to point its antenna perfectly at Earth all the time to send signals.
For example, on HADES‑ICM satellite, we used a special soft antenna that can pop out like a spring. It’s light and easy to pack for launch. Once the satellite reached orbit, the antenna unfolded smoothly and quickly started sending out its signals within the first few trips around the Earth.
Communicating in Real Time (Sort Of)
Using UHF and VHF radio isn’t about sending super-fast videos or live streams—you won’t be watching HD movies from a PocketQube anytime soon.
Instead, these satellites send little bursts of information called packets. Think of packets like tiny envelopes carrying important updates—things like the satellite’s health, where it is in space (GPS coordinates), sensor readings, and results from experiments onboard.
For example, our HADES‑ICM satellite sends out these packets using a format called AX.25—which is a common language many amateur radio operators and satellite enthusiasts use to communicate. Inside these packets, you’ll find important details like battery levels, internal temperatures, system status, and how long the satellite has been operating.
On the ground, stations—both ours and those run by volunteers worldwide—use special radios called Software-Defined Radios (SDRs) to listen and decode these packets in real time. This global network of listeners is what keeps small satellites visible and connected, even when budgets are tight and resources limited.
UHF vs. VHF: What’s the Difference?
Remember how we talked about VHF as the satellite’s “beacon light” that sends simple signals, and UHF as the “two-way walkie-talkie” for sending and receiving messages?
Now, let’s look at the strengths and tradeoffs of these two radio types:
VHF (the beacon light):
· Its signals can travel farther at the same power—like a bright flashlight reaching far into the night.
· It doesn’t get weakened much by the air around us.
· And it can work with very simple, basic antennas.
But, to get the best signal, VHF antennas tend to be larger—so they take up more space. Also, the VHF frequency band can get crowded, limiting how much data can be sent.
UHF (the two-way walkie-talkie):
· Has smaller antennas that fit well on tiny satellites.
· Can send data faster, which is great for more detailed information.
· Works well with flexible radios called Software-Defined Radios (SDRs).
However, UHF needs a bit more power, and because its signals are higher frequency, it’s more sensitive to how the satellite is positioned and pointed.
For our icMercury mission, we chose UHF because it balances simplicity and good performance. Plus, it lets us connect with a vibrant community of amateur satellite listeners—some of our most helpful partners!
Software-Defined Radios: A Game Changer
Not long ago, receiving satellite signals required custom hardware. Today, SDRs have transformed the landscape.
We use SDRs both on the ground and in orbit. They allow us to:
- Switch between protocols (AX.25, BPSK, GMSK)
- Test new communication modes mid-mission
- Remotely adjust transmission parameters
It’s like having a radio that can reinvent itself after launch. And when your satellite is already hundreds of kilometers above Earth—far beyond reach—that kind of flexibility becomes incredibly valuable.
A Tool for Global Participation
One of the best things about using UHF and VHF frequencies is how easy they are to access. You don’t need expensive, high-tech gear to listen to a small satellite flying overhead. Even a student with a simple antenna, a small radio device called an SDR dongle, and a little patience can tune in and hear signals from space.
We’ve gotten messages from high school clubs in Spain, hobby radio fans in Germany, and teachers in Southeast Asia—all listening and sharing data from PocketQube satellites. That’s the real magic of these frequencies: they open the door to space for everyone.
And when we say we want to make space accessible to all, it’s not just a slogan. This is exactly how it’s happening.
Sharing the Stage Globally
This November, Interstellar Communication Holdings Inc. will take part in the 2025 Go Global Awards in London, hosted by the International Trade Council. For us, this is more than just an award—it’s about building connections.
We’re joining a worldwide group of innovators who are opening new paths in technology, science, and communication. And our story is simple: even the smallest satellite, using the simplest radio, can reach people all around the world.
We’re proud and excited to share this message on the global stage.
Final Thoughts
In a world full of laser links and high-tech quantum signals, it’s easy to forget about the simple power of UHF and VHF. But these radio waves—quiet, reliable, and well understood—are still the lifeline that keeps small satellites connected all over the world.
They’re more than just tools—they’re open invitations. To listen. To build. To connect. And maybe, that kind of connection is exactly what space needs today.
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Disclaimer
All satellite communications and frequency usage described in this article are conducted in full compliance with applicable national and international regulations.
Interstellar Communication Holdings Inc. operates exclusively on authorized amateur and/or educational frequency bands, and any data transmitted from our small satellites—such as beacon packets—are intentionally designed for open, public reception.
We fully respect global spectrum coordination policies and support responsible, transparent use of space technologies.
Mentions of ground-based signal reception by students, educators, and amateur operators refer only to legally permitted activities involving publicly accessible signals. No proprietary or sensitive data is ever transmitted or disclosed.
