In-situ high field strength testing using a transportable reverberation chamber

A reverberation chamber can create very high field strength with moderate input power. Existing chambers are making use of a paddle wheel to change the resonant modes in the chamber. In the case of a stepper motor, the field is stable for some time, and this type of reverberation chamber is called mode tuned reverberation chamber. If the paddle wheel is continuously rotating we call it a mode stirred reverberation chamber. The mode stirred is much faster in measuring than the mode tuned, but for some applications where the equipment under test has a long dwell time the mode tuned is preferred. A transportable reverberation chamber with varying angles between wall, floor and ceiling and with vibrating walls has been used for in-situ testing of a large radar antenna system. Inside this Vibrating Intrinsic Reverberation Chamber (VIRC) a diffuse, statistically uniform electromagnetic field is created without the use of a mechanical, rotating, mode stirrer. This chamber results in a better homogeneity and increased field strength compared to conventional mode stirred reverberation chambers. But the VIRC has a disadvantage because it cannot be used for mode tuning. In this paper also a tuneable intrinsic reverberation chamber (TIRC) is presented. The chamber is still made of flexible material and thus transportable, but the modes are changed using either a paddle wheel or by moving the walls in small incremental steps.