Interaction of biological tissue with electromagnetic waves in the RF range

Abstract

Summary form only given. The investigation of the interaction of biological tissue, i.e. cells, organs or living being, and electromagnetic waves has been of interest to the scientific community for a very long time, but became a research focus with the introduction of mobile phones in the 1990-ies. The primary natural source of RF fields is the sun. Human-made sources, however, emit the majority of fields in the immediate environment of the community, home or the workplace. Most RF fields found in the environment are due to commercial radio and TV broadcasting and to telecommunications facilities. RF sources in the home include microwave ovens, DECT telephones and Wi-Fi routers. In the workplace, there are a number of industrial processes which use RF fields: dielectric heaters used for wood lamination and the sealing of plastics; industrial induction heaters and microwave ovens. Today the largest source of RF for the general public is the use of mobile telephones. Except when phones are used in a hands-free position or used to send data, mobile telephones are generally held against the head when a call is being made and the antenna receives and sends the signal. The head of the user is in the near field of the source because of the distance of the antenna to the head is typically a few centimetres. Due to this close proximity, the interaction of RF energy has to be considered due to possible destructive effects. This talk will give a comprehensive overview of the different identified interaction mechanisms and explain their physical principles, and will outline ways to approach the understanding of the mechanisms either by numerical simulation or measurement. Additional information will be given on the most important effect: the thermal heating of tissue which is exposed to electromagnetic waves. The fundamental criteria are explained, including a detailed discussion of the Specific Absorption Rate (SAR) and various ways to estimate the SAR values for different tissues. The talk will include a review of the relevant literature, the most cited overview articles and publication database. Concluding, a short statistical investigation will be given on the possible health effects.