科研之友
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摘要
A Transverse Electromagnetic Mode (TEM) cell is one interesting alternative for studies of biological effects of radiofrequency radiation at reduced scale (in vitro studies). Controlled and well-characterized exposure conditions are essential for a concluding investigation: the biological sample has to be exposed to a uniform incident electromagnetic wave and the dose of absorbed radiation has to be precisely determined and correlated with the effect. Unfortunatelly, many times experimental dosimetry is either unavailable or unappliable, so that a pre-characterised and validated experimental set-up is mostly valuable. In this regard, the main objective of present work was to experimentally validate a computational model of an own-built TEM cell designed for bioelectromagnetic experiments in frequency range of 100MHz-1GHz. For validation, three significant parameters were investigated comparatively, by measurements and by computation: scattering parameters; incident electric field distribution; absorbed power in a set of liquid samples. By using the finite integration technique (FIT) method implemented by the commercial code CST Microwave Studio, and by using a vector network analyzer in the experimental approach, we validated the designed TEM cell and characterized it successfully. The second objective was a dosimetric study of four different liquid samples loaded in the cell. We used the absorption coefficient (AC) which may be assimilated to the specific absorption rate (SAR) of energy deposition in the whole sample volume. AC was shown to converge in experiment and simulation up to 800MHz for all samples. AC didn't depend directly upon samples volume (even if, frequently, greater volumes showed higher absorption) but rather upon the internal field distribution in the sample, distribution that mostly depends on the frequency and on the dimensions of the liquid samples.
- 出版日期2012
