Sub-GHz, NFC, and RFID Technologies Explained

Wireless tech is one of those things we use every day without really thinking about it. Smart home sensors, access cards, contactless payments, garage remotes. A lot of it runs on Sub-GHz, NFC, or RFID.

Recently, I got curious about how these technologies actually work and what security implications they come with. Once you start looking into them, you realize how much of our daily tech relies on simple radio communication. This post is basically a breakdown of what I’ve learned so far.

In this post, I’ll go through what these technologies are, how they work in practice, and what to be aware of from a security and privacy perspective.

Sub-GHz

Sub-GHz is all about range and efficiency. It refers to radio frequencies below 1 GHz, typically around 300–868 MHz in Europe and 915 MHz in the US. These frequencies travel far, pass through obstacles well, and don’t require much power, which is why they’re so widely used in wireless systems.

How Does It Work?

Sub-GHz communication sends small amounts of data over radio waves that behave very differently from Wi-Fi or Bluetooth. Lower frequency means better penetration and longer range, but lower speed.

That tradeoff makes Sub-GHz ideal for devices that just need to send simple status updates rather than large amounts of data.

Example Uses in Real Life

• Smart Meters and Home Automation: Devices that report readings or state changes over long distances.
• Agricultural Sensors: Monitoring crops or livestock across large fields where Wi-Fi wouldn’t make sense.

Pros and Cons

For all its benefits, Sub-GHz isn’t without its drawbacks. While it’s great for long-range communication, it’s slower than higher-frequency technologies like Wi-Fi or Bluetooth. Additionally, its long-range capabilities can make it vulnerable to hacking attempts from a distance.

NFC

NFC is all about proximity. It’s the tech behind contactless payments, after all. Operating at 13.56 MHz, it facilitates communication between devices a few centimeters apart. It’s the technology equivalent of a secret handshake that only works when you’re super close.

Because of that short range, NFC is generally considered safe. Still, it’s worth being aware of what you tap your phone against. A malicious NFC tag can trigger unwanted actions if you’re not paying attention. For example, it could download unwanted data or even malware, open a website, or even connect to a rogue Wi-Fi network. So while NFC is generally secure thanks to its limited range, staying mindful of what you’re connecting with is crucial.

How Does It Work?

NFC works using an initiator and a target. The initiator generates a radio field that powers the target, which is often a passive chip like a payment card or tag. Data is exchanged almost instantly once the devices are close enough.

Example Uses in Real Life

• Contactless Payments: Paying by tapping your phone or card.
• Smart Posters and Tags: Tapping a tag to open a website or app.

Pros and Cons

The short range is NFC’s biggest strength and its biggest limitation. It’s great for security and convenience, but it also means NFC isn’t useful for anything beyond very close-range interactions.

RFID

Radio Frequency Identification (RFID) uses electromagnetic fields to identify and track tags attached to objects. Think of it as a barcode but wireless and way more versatile. RFID operates at various frequencies, from low to high, and can be passive (powered by the reader) or active (with its own power source). It can scan multiple items simultaneously, making it an efficient solution for inventory management, libraries, and access control systems.

However, RFID isn’t without its vulnerabilities. The tags can be scanned from a distance, sometimes without your knowledge, which could lead to unauthorized tracking or data interception.

How Does It Work?

An RFID system consists of a tag, a reader, and an antenna. The reader emits a signal, the tag responds with its identifier, and the system processes that information.

Example Uses in Real Life

• Inventory Management: Tracking goods in warehouses and stores.
• Access Control: Office badges and key cards.

Pros and Cons

RFID’s ability to scan multiple items at once and work over various distances makes it very powerful. But if security isn’t handled properly, it also opens the door to unauthorized scanning or tracking.