SAR Specific Absorption Rate

Specific Absorption Rate (SAR) is a measure of the rate at which electromagnetic energy is absorbed by the human body when exposed to radiofrequency (RF) electromagnetic fields. SAR is typically expressed in units of watts per kilogram (W/kg).

When we use electronic devices such as mobile phones, tablets, or wireless devices, they emit RF radiation, which is a form of non-ionizing radiation. SAR quantifies the amount of RF energy that is absorbed by the body tissues in proximity to the device. It is used to ensure that the exposure to RF radiation remains within safe limits and does not cause harm to human health.

The SAR value is determined through scientific testing and measurement techniques. During these tests, a model of the human body, often referred to as a phantom, is used. The phantom simulates the physical properties of human tissues and is filled with a liquid that mimics the electrical conductivity of human body fluids.

The SAR measurement is performed by placing the device near the phantom and measuring the amount of RF energy absorbed by the phantom. The SAR value is then calculated by dividing the absorbed power by the mass of the phantom.

To comply with regulatory guidelines, electronic devices are tested to ensure that their SAR values are within the permissible limits. These limits are set by various international organizations, such as the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and the Federal Communications Commission (FCC) in the United States.

The SAR limits vary depending on the frequency range and the specific body parts exposed to RF radiation. For example, in the United States, the FCC has set a maximum SAR limit of 1.6 W/kg averaged over 1 gram of tissue for the head and trunk, and 4 W/kg averaged over 10 grams of tissue for the limbs.

It is important to note that SAR is a measure of the thermal effects of RF radiation, meaning it assesses the potential for the energy to heat body tissues. It does not take into account non-thermal effects, such as possible long-term biological effects that may occur at lower exposure levels.

Manufacturers of electronic devices are responsible for ensuring that their products comply with SAR regulations. They achieve this through various design strategies, such as optimizing antenna placement, reducing power transmission levels, and implementing techniques to minimize RF energy absorption by the body.

Consumers can access SAR information for electronic devices either through product documentation or the manufacturer's website. This allows individuals to make informed decisions about their device usage and compare SAR values between different products.

In summary, SAR is a measure of the rate at which RF energy is absorbed by the human body when exposed to electromagnetic fields. It helps regulate the safe use of electronic devices and ensures that the energy absorbed by the body remains within acceptable limits to minimize potential health risks.