Many owners of Xiaomi smartphones, delving into the technical characteristics of the device or reading the specifications on the box, are faced with a mysterious acronym. SAR. A question that often arises is, is this the name of some particular physical sensor inside the housing that you can disable or configure, SAR-The sensor as a separate component that the user could find in the task manager or settings menu does not exist in the usual sense.
This is often confused with real-world hardware sensors like an accelerometer or proximity sensor, but SAR is a critical safety measure that engineers calculate during development and are validated by laboratory tests, which determines how much electromagnetic energy the human body absorbs when using Xiaomi.
In this article, we will discuss in detail why this parameter is important for your health, how manufacturers including Xiaomi, Redmi and POCO comply with international standards, and whether you can independently influence radiation levels.
The physical essence of SAR and the myth of the sensor
The first thing to learn is that Xiaomi smartphones don’t have a separate chip called the SAR sensor, which constantly monitors radiation and displays data on the screen. SAR (Specific Absorption Rate) is a calculated value, measured in watts per kilogram (W/kg), which shows the rate at which the energy of the radio frequency field is absorbed by the body’s tissues.
When you hold your phone to your ear while you're talking or carry it in your pocket, the device's antennas emit radio waves. Some of that energy passes through your body and some is absorbed. SAR rationing is necessary to prevent tissue overheating and potential negative effects on biological processes. Xiaomi engineers design antenna modules so that even at maximum power, the signal remains within safe limits.
⚠️ Note: Don’t try to find it on the menu MIUI or HyperOS switch"SAR Sensor. It doesn't exist. Any third-party apps that promise to run SAR", They are fakes and may contain malicious code.
There is a common misconception that the proximity sensor that turns off the screen when you hold the phone to your ear is somehow related to SAR control. It's not. The proximity sensor only saves battery power and prevents accidental cheek pressing, but it doesn't regulate transmitter power based on body absorption.
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Remember: SAR is a passport characteristic of a model, not a dynamic parameter that changes in real time depending on how you hold your phone.
Xiaomi International Safety Standards and Standards
All smartphones entering the global market, including Xiaomi products, must undergo strict certification. CE standard in Europe, which limits the SAR value to 2.0 W / kg for the head and trunk. In the United States, the FCC requirements are slightly stricter, at no more than 1.6 W / kg. Chinese regulations are also strictly regulated and often coincide with international ones.
Xiaomi is testing its devices in two main modes:
- 📱 To the head: Simulates a phone conversation when the device is pressed against the ear.
- 👖 At the body: Simulate wearing in a pocket of pants or shirts at a distance of about 5-15 squirt.
It's important to understand that the data is the highest possible value, recorded in the worst communication conditions. In real life, when the network signal is stable, the phone is running at the lowest power, and the actual SAR is well below the limit values.
Comparative table of limit norms and typical values for smartphones:
| Region/Standard | SAR (head/body) limit | Typical SAR Xiaomi (max) | Unit of measurement |
|---|---|---|---|
| Europe (CE) | 2.0 | 0.5 - 1.2 | W/kg (10g tissue) |
| United States (FCC) | 1.6 | 0.4 - 1.1 | W/kg (1 g of tissue) |
| China (SRRC) | 2.0 | 0.5 - 1.3 | W/kg (10g tissue) |
| Russia (EAEU) | 2.0 | 0.5 - 1.2 | W/kg (10g tissue) |
As you can see from the table, even the maximum performance of Xiaomi devices is usually far below the critical line, which provides a margin of safety.
Where to find SAR information for your model
Users often look for specific numbers for their Redmi Note or Mi. The most reliable way is to refer to official documentation. Usually this data is at the end of the user's instructions (guide) in the "Specification" or "Security" section.
If the paper instruction is lost, you can use digital methods. Many global versions of MIUI firmware have certification data available on the system menu. Go to Settings → About Phone → All specs (or a similar path depending on the OS version). However, specific SAR numbers are rarely written there, more often indicate compliance with standards.
A more accurate way is to search the official Xiaomi website in the support section of a particular model or on the websites of regulators (for example, the official website of Xiaomi, FCC ID You will need to know the exact model name, for example, M2101K7BNY.
⚠️ Attention: Values SAR The same model may differ for the same model but released for different markets (Chinese vs Global) due to differences in antenna modules and frequency bands.
How to find FCC ID on the case?
Factors affecting the radiation level of the smartphone
The SAR level is not a constant for the device that is running; it changes dynamically depending on the operating conditions; the transmitter power is automatically controlled by the base station; if you are in a confident reception zone, the phone emits minimal energy.
The main factors that increase SAR in real time:
- 📶 Weak network signal: When indicator 1 is dividing or the "H"/"E" icon, the phone increases the antenna power to maintain the connection.
- 🚄 Moving: When moving at high speed (train, car) the phone switches between towers more often, which increases the activity of the communication module.
- 📡 Access Points: Internet distribution (modem mode) via Wi-Fi or Bluetooth also uses antennas at higher power levels.
It is worth noting that the use of 5G networks can theoretically require more complex antennas, but modern standards Xiaomi with Beamforming technologies direct the signal more accurately at, reducing the overall background radiation in the side.
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The greatest radiation does not occur during a conversation, but when you search for a network or download large files when a bad signal is present.
Practical advice on reducing radiation exposure
While Xiaomi smartphones are safe, the precautionary principle has not been abolished. If you want to minimize the effects of electromagnetic fields on the body, follow simple guidelines, which is especially true for children and people with implanted medical devices.
Here are the effective ways to reduce exposure:
- Use a headset or speakerphone, remove the phone from your head, even on the phone. 10-15 cm reduces energy absorption by tens of times.
- Do not carry your phone in your trouser pocket close to your body unless you need to, but use a bag or chest pocket.
- Avoid long conversations in elevators, basements, and subway trains where the phone is running at power limit.
There's a myth about "protective stickers" on an antenna, and the physics of radio wave propagation is that shielding part of the antenna only causes the phone to automatically increase the power to punch through the screen, which ultimately increases the overall energy consumption and heating, but does not reduce the SAR.
☑️ Checklist for safe use
Influence of covers and accessories on the signal
Accessories can significantly affect the operation of Xiaomi antennas: Metal cases, magnetic clasp cases or thick rubber cases can create a “screen effect”. In response to the deterioration of communication quality, the smartphone increases the power of the transmitter.
If you notice that the phone is getting hotter or discharged faster in a particular case, it may be the case that blocks the signal. In such cases, the SAR does not formally change (as this is a characteristic of the device itself), but local heating and working at the limit of capabilities may not be desirable.
It is recommended to choose accessories that have cutouts for antenna lines (usually visible as plastic inserts on the ends of the case), which will provide a stable signal without the need to increase the radiation power.