Changes in specific absorption rate in the head due to metallic gap loops and a simulated mobile phone source in a study of the effects of jewellery

This paper investigates Specific Absorption Rates (SAR) in the human head due to partial metallic gap loops (incomplete circular jewellery rings) at 1800MHz. A Finite-Difference Time-Domain (FDTD) code was used to analyse different sizes and positions of circular rings with a section removed, near a homogenous cubic phantom with a dipole excitation. These partial loops significantly increased the SAR. Measurements from a DASY4 measurement system as well as commercial code results are used for validation. The FDTD code has also been used to analyse the effects of metallic jewellery gap loops when added to the nose of an anatomically realistic digital human head with a realistic source. A monopole on a box was placed in front of the face to represent a PDA. The gap loops on the nose of the realistic head behaved similarly to those near the cubic head. Gap loops of different sizes resonated when their orientation were changed. This means that smaller sizes of jewellery, in certain geometries, may resonate when used with mobile communications equipment than was previously expected.