Development of a mode stirred EMC facility

Recent advances in technology have enabled increasingly high powered radars to be developed. This impacts on the EMC test of military systems because defence equipment has to be tested for susceptibility to the new higher field levels. These field strengths have to be generated over a wide frequency band. At microwave frequencies average levels of 1-10 kV/m, and peak levels of 1020 kV/m, are likely. It is thus necessary for the defence industry to develop methods of testing at such high field levels. The mode stirred chamber is one option for generating high electric fields. This paper describes the first steps in the development of a mode stirred chamber in the EMC test facility at BAe Dynamics Limited, Bristol. Several candidate screened rooms in the facility were considered for conversion into a mode stirred chamber. The prime consideration in the chamber choice was the field strength achievable. The assessment involved a study of the resonant properties of each potential chamber, and calculation of Q factors and electric field levels. This data, together with practical considerations, enabled a choice of the chamber for development to be made