A novel technique for damping site attenuation resonances in shielded semi-anechoic rooms

Presents a simple and economical technique for suppressing resonance problems in shielded semi-anechoic rooms (SSARs). The work described is an application to an SSAR of a technique developed by Dawson and Marvin for small shielded enclosures. It consists of putting lossy dielectric blocks at well-selected positions where the electric fields of the problem-causing resonant modes show up a maximum. The chamber was designed primarily to perform EMI measurements at 3 m distance. However, it is also being used for irradiation measurements. Site attenuation measurements were performed in the 30-1000 MHz band to check the performance of the chamber