Specific Absorption Rate and Maximum Permissible Input Power of Planar Inverted-F Antennas

The study has emphasized the primary contributions and findings in the following highlights: • Specific Absorption Rate (SAR) assessments were performed on the PIFAs at various mobile operating frequencies ranging from 0.835 GHz to 2.6 GHz by simulation and measurement. • The SAR was examined in relation to both variable and constant input power to identify the factors influencing the SAR values. • The SAR investigation was carried out with varying input power, and the study found a correlation between SAR and input power, mass of tissues, and frequency. The findings indicate that increasing input power has caused the SAR level to increase for all frequencies, that a smaller mass of tissue has a higher SAR value because of the more concentrated power absorption, and that frequency does not directly influence SAR, indicating the presence of another factor that could affect SAR. • The study discovered additional factors that affect the SAR value with a fixed input power, which the finding demonstrates that SAR is proportional to PIFA gain. • The SAR investigation on PIFA's maximum permissible input power was conducted to ensure compliance with the exposure limits, and the finding shows that the maximum permissible input power is related to the PIFA gain. The electromagnetic wave radiation toward human heads has gained attention due to a large number of mobile phone usage, especially concerning the planar inverted-F antenna (PIFA), which is commonly used in these devices. Therefore, it is essential to investigate the radiation from mobile phones utilizing PIFA across mobile operating frequencies. Hence, this article investigates the specific absorption rate (SAR) of a rectangular-shaped planar inverted-F antenna (PIFA) at frequencies ranging from 0.835 GHz to 2.6 GHz. These PIFAs are implemented as the radiation source to investigate the SAR at the concerned mobile operating frequencies through simulation and measurement focusing on various input power, antenna gain, and antenna maximum permissible input power for SAR compliance. The PIFA is placed at a distance of 10 mm from the human head phantom in the investigation. The results show that operating frequency is not a primary factor influencing the level of SAR on PIFA, as highlighted in the previous works. However, it is noted that the SAR of PIFA is proportional to the input power and volume of mass tissue. Higher input power leads to a higher SAR value as more radiated energy is absorbed by the human head, while the lower mass of tissue results in the higher SAR due to the higher concentration of power absorption for the smaller tissue mass. Furthermore, a key finding reveals that the SAR of PIFA follows the same trend as its gain. The increment of gain enhances the radiation efficiency of the antenna, which subsequently increases the absorption level within the human head, leading to a higher SAR. In order to comply with the standard limit, the PIFA's maximum permissible input power also follows the trend of antenna gain, with 1 g of mass tissue needing a lower maximum permissible input power compared to 10 g of mass tissue.