SAR (special absorption rate) & frequency

In summary, the conversation discusses the relationship between wavelength, frequency, and energy, as well as the concept of Specific Absorption Rate (SAR) and its behavior when calculating it for human brain tissue. The speaker also mentions the importance of not confusing quantum properties with classical problems and how power absorption is affected by various factors. The speaker also points out that SAR is a measure of the amount of energy absorbed per kilogram of tissue.
  • #1
Worldline
23
0
Hi
we know the relation between wavelength, frequency and energy :
The greater the energy, the larger the frequency and the shorter (smaller) the wavelength -> E=h[itex]\upsilon[/itex]
On the other side, SAR is common property that measures absorbed energy.
Now if we calculating SAR for human brain tissue , we would have such graph :
SAR.jpg


But i don't understand why it behaves like that , why SAR doesn't increase with frequency ?
 
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  • #2
There's no graph, so I don't know what exactly you are referring to. In general, you shouldn't confuse quantum properties with the classical problem you are considering. Power absorption depends on geometry, EM wave coupling, and on the square of the amplitude of the wave. Coupling depends only weakly on frequency. As frequency rises, eddy currents are induced and dissipated in the highly conductive tissue. Higher frequencies don't change this until you get high enough to limit penetration due to skin depth shielding.

PS: It's Specific (not special) Absorption Rate. Specific means amount per kg of tissue.
 
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FAQ: SAR (special absorption rate) & frequency

What is SAR (Special Absorption Rate)?

SAR (Special Absorption Rate) is a measure of the rate at which energy is absorbed by the human body when exposed to radio frequency electromagnetic fields. It is typically measured in watts per kilogram (W/kg) and is used to evaluate the potential health risks of exposure to radio frequency energy.

What is the relationship between SAR and frequency?

The SAR value is affected by the frequency of the electromagnetic field. Higher frequencies typically result in higher SAR values, as the energy is more concentrated. However, the relationship between SAR and frequency is complex and can also be influenced by other factors such as the size and shape of the body part exposed to the field.

What are the health risks associated with SAR?

The health risks associated with SAR exposure are still being studied and debated. Some studies have suggested a potential link between high levels of SAR exposure and certain types of cancer, while others have found no significant health effects. The World Health Organization (WHO) states that current evidence does not confirm any health consequences from exposure to radio frequency fields at levels below the international guidelines.

What are the safety guidelines for SAR exposure?

The International Commission on Non-Ionizing Radiation Protection (ICNIRP) has established guidelines for exposure to radio frequency electromagnetic fields, including SAR levels. These guidelines are regularly reviewed and updated based on the latest research. In general, the guidelines recommend keeping SAR levels below 2 W/kg for the general public and below 4 W/kg for workers with occupational exposure.

How can I reduce my SAR exposure?

To reduce your SAR exposure, you can limit the amount of time you spend using devices that emit radio frequency energy, such as cell phones and Wi-Fi routers. You can also use hands-free options, such as speakerphone or a headset, to keep the device away from your body. Additionally, using devices with lower SAR values and following manufacturer's instructions for safe use can also help reduce your exposure.

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