Analysis of the Transmitted Field Amplitude and SAR Modification Due to Mobile Terminal - Flat Phantom Multiple Interactions

When a lossy scatterer or ´phantom´ is located in the near-field of a radiating source, complex/multiple interactions occur, which generally affect the field actually impinging on-and transmitted in-the phantom. In this paper, the contribution to the field transmitted in a flat phantom coming from the ideally unaltered free-space field of numerical mobile phones models, radiating at 900 and 1800 MHz, is isolated thanks to plane-wave expansion, and the additional contribution resulting from the interaction is analyzed. It appears that, even for small terminal-phantom distances down to 2.5 mm, the field topography inside the phantom can be globally determined from the free-space field, whereas the amplitude of the ´spot´ (and hence the averaged Specific Absorption Rate) may be significantly modified by multiple interactions. It is also shown that the consequences of the interactions on the transmitted field may strongly differ depending on the position of mobile phone antenna with respect to the phantom.