Wi-Fi and Bluetooth get all the attention at 2.4 GHz, but a huge amount of everyday wireless happens below 1 GHz, out of sight. "Sub-GHz" is the umbrella term for those lower bands. They are slower than Wi-Fi, but they travel further, pass through walls better and sip power — which is exactly what a battery sensor or a garden gate needs.
01What "sub-GHz" means
Sub-GHz means any radio below 1 gigahertz. In everyday hardware it is shorthand for a handful of licence-free ISM bands clustered around 315, 433, 868 and 915 MHz. ISM stands for Industrial, Scientific and Medical: ranges set aside by regulators where you can operate low-power equipment without an individual radio licence, as long as you respect the power and duty-cycle limits for that band.
The reason these bands exist in different places is history and regulation. There is no single worldwide sub-GHz band, which is why a remote bought in the US and one bought in Europe often use different frequencies.
02Why lower frequency means longer range
A radio wave's frequency and its wavelength are two sides of the same coin: lower frequency means a longer wavelength. At 433 MHz the wave is about 69 cm long; at 2.4 GHz it is about 12 cm. That length difference drives three practical effects.
- Less path loss. For the same transmit power and antenna, a lower-frequency signal loses less energy as it spreads out, so it is still readable further away.
- Better penetration. Longer waves bend around and pass through walls, furniture and foliage more easily. A 2.4 GHz signal is absorbed quickly by a brick wall or a wet hedge; a sub-GHz signal shrugs more of it off.
- Lower data rate. The catch. A narrow, low-frequency channel carries fewer bits per second. You get reach and robustness, not bandwidth.
That is the whole personality of sub-GHz, and it is the trade-off drawn in the chart above: pick a lower band when you need a sensor to report a few bytes from far away through walls, and a higher band when you need to move real data quickly over a short hop.
03The licence-free bands by region
Which band you can legally use depends on where you are. These are the common ones and their typical roles:
| Band | Mainly used in | Typical devices |
|---|---|---|
| 315 MHz | United States / North America | Car key fobs, garage and gate remotes, TPMS tyre sensors |
| 433 MHz | Europe and much of the rest of the world | Remotes, weather stations, cheap sensors, hobby links |
| 868 MHz | Europe | Smart home sensors, metering, LoRa and LoRaWAN |
| 915 MHz | United States / North America | ISM links, industrial telemetry, LoRa and LoRaWAN |
04What runs on sub-GHz
Once you know what to look for, sub-GHz is everywhere. It is the default choice whenever a device needs long battery life and decent range for small amounts of data.
- Remote sensors. Door and window contacts, soil-moisture probes, tank levels and leak detectors that must run for years on a coin cell.
- Weather stations. The outdoor unit sends temperature, humidity, wind and rain to the indoor display over 433 or 915 MHz.
- Industrial telemetry. Factories and farms collect readings from machines and tanks spread across a wide site.
- Smart meters. Utility water, gas and electricity meters report usage wirelessly, often on 868 or 915 MHz.
- LoRa and LoRaWAN. Long-range, low-power networks for city-scale IoT, built on the 868 and 915 MHz bands.
- Remotes and fobs. Garage doors, gates and alarm keypads, usually on 315 or 433 MHz.
05Modulation basics: OOK, FSK and LoRa
A band is just a place in the spectrum. Modulation is how you write data onto the carrier wave living there. Three families cover almost everything you will meet in sub-GHz.
| Type | How it works | Where you see it |
|---|---|---|
| OOK / ASK | Switches the carrier on and off (amplitude). Simple and cheap. | Basic remotes, fobs, low-cost 433 MHz sensors |
| FSK | Shifts between two (or more) frequencies. More robust against noise. | Weather stations, meters, many ISM sensors |
| LoRa (chirp) | Sweeps the frequency across the channel. Trades speed for huge range and sensitivity. | LoRaWAN, long-range IoT, off-grid links |
- OOK/ASK (On-Off Keying / Amplitude-Shift Keying) is the simplest: a "1" is the carrier turned on, a "0" is it turned off. Cheap to build, but easily disturbed by noise.
- FSK (Frequency-Shift Keying) encodes bits as small shifts in frequency. Because it ignores amplitude, it rides through interference far better, which is why sensors and meters favour it.
- LoRa uses chirp spread spectrum — a smooth frequency sweep — to pull signals out of the noise. It is slow but reaches kilometres, which is why it underpins long-range IoT.
06Working with your own devices and sensors
Understanding sub-GHz is most useful when you are building or maintaining your own equipment: choosing the right band for a sensor you are deploying, checking that your own LoRa node is on the frequency you intended, or seeing how busy a band is before you add another device to it. A sub-GHz transceiver lets you observe the spectrum your own gear uses so you can design and debug a clean link.
The SGP Card Mini carries a TI CC1101 sub-GHz transceiver alongside its SX1262 LoRa radio. Within the licence-free limits of your region, it is a handy tool for spectrum analysis of your own lab devices: watching activity on a band, confirming a sensor you own is transmitting where you expect, and learning how OOK and FSK links behave. It is an educational, development-focused tool for the hardware you build and own.
07FAQ
What does sub-GHz mean?
Sub-GHz simply means radio below 1 GHz. In practice it refers to the licence-free ISM bands near 315, 433, 868 and 915 MHz used by sensors, remotes, meters and long-range links, as opposed to the 2.4 GHz band used by Wi-Fi and Bluetooth.
Why does a lower frequency travel further?
Longer wavelengths lose less energy over distance and pass through walls and foliage more easily, so for the same transmit power a sub-GHz signal generally reaches further and penetrates buildings better than a 2.4 GHz one. The trade-off is a lower maximum data rate.
Which sub-GHz band can I use in my country?
It depends on the region. The United States uses 315 MHz for many remotes and 915 MHz for ISM links. Europe uses 433 MHz and 868 MHz. 433 MHz is also widely available across much of the rest of the world. Always use the band and power limits your local regulator allows.
What is the difference between OOK, FSK and LoRa?
They are ways of putting data onto the carrier. OOK/ASK switches the carrier on and off and is simple and cheap. FSK shifts between two frequencies and is more robust, so it is common in sensors and meters. LoRa uses a sweeping chirp that trades data rate for very long range and high sensitivity.