Simulation of electromagnetic field exposure in resonant environments (SEFERE)

Wireless communication is key to many schemes to reduce the environmental impact of transport or to provide the pervasive network access needed for future urban environments (including vehicle passengers). Thus, electromagnetic safety is a major issue in the design, operation and public acceptance of such systems. The EU has recently published limits for electromagnetic field exposure, but they do not readily apply to resonant environments such as vehicles and buildings. Also, the field distributions that arise in these structures are so complex that reliable assessment of the exposure by measurement is not practicable.

This project therefore concerns the development and experimental validation of large-scale simulation methods to assess the characteristics of fields due to radio transmissions in such environments. Model content, analysis methods, efficient simulation strategies and field mitigation techniques will be addressed, using car and aircraft based case studies.

Internal fields and surface currents for a car with GSM 900 MHz antenna

There is currently little understanding of how electromagnetic fields generated from mobile devices are distributed within the cavities formed in buildings or the cabins of cars, trucks or aeroplanes. Hot spots of radiation will be created dependent on the antenna location, the frequency, the soft furnishings and the distribution of humans and luggage within. It is necessary to determine how onboard antennas affect the exposure of humans to radiation and the effect of radiation on EMC issues.

This project therefore aims to understand the extremely complex distribution of fields within such cabin environments over a range of frequencies from the Tetra band near 400MHz to the higher networking bands around 6GHz. The project will study how fields are formed within passenger cabins and examine ways of reducing their intensity either by positioning the antenna in a suitable position or by strategically placing microwave radiation absorbing material and frequency selective structures within the cabin. The experimental validation of such simulations also presents very significant difficulties, requiring the mapping of large spatial volumes within complex structures. Thus, a flexible, automated and low-disturbance positioning system will need to be developed.

This project is part of a DTI Technology Programme and the partners include MIRA, BAE, Volvo Cars, Harada, Jaguar Cars, ARUP and PITO.