The Effect of Proximity Sensor & Grip Sensor Use on Specific Absorption Rate (SAR) in Smartphones

Today, with the contribution of the new generation of communication technologies, many smart devices are produced. Almost every electronic device, including smart phones, smart watches, wireless headphones, tablets, emits some form of radiation. While most of this electromagnetic radiation is harmless, some of it can have potential health effects, depending on the frequency of use over long periods of time and in close usage. Specific Absorption Rate is a measure of how much human body tissue absorbs energy when the body is exposed to radiation. This measurement helps determine whether a device is safe for regular use. The SAR value may vary depending on the antenna and schematic design of the smartphone. To support high band requirements for 5G smartphones, more RF antennas required to be added in PCB design. When designing smartphones, designers also need to design proximity-grip sensors that accurately meet the industry's Specific Absorption Rate (SAR) requirements. In this study, the effects of proximity and grip sensors used in smartphones on LTE and 5G NR SAR values are investigated. During these measurements, a combination of Grip and Proximity Sensors were alternately turned on and off. Although the proximity sensor and grip sensor are not mainly used to optimize SAR values, it is foreseen that they may have indirect effects on SAR. In this context, SAR measurements were made in 3D environment for different frequencies. As a result of this study, it was observed that the grip-proximity sensors used in smartphones significantly reduce the SAR value and transfer less energy to the users in close range use. The effect of using the proximity sensor on the SAR rate was measured to be approximately 8%, while the effect of using the Grip Sensor was observed to be approximately 10%.