The improvement of the resonance in RFI chamber

Reported improvements in resonances observed in a semianechoic radio frequency interference (RFI) measurement chamber are discussed. Due to the chamber's construction details and antenna placement, for 90 MHz measurements one point within the chamber had decreased electric-field intensity while another point showed the opposite. After lining the chamber's ceiling and for walls with about 13000 ferrite tiles, the points with unusually high or low field strengths were almost totally eliminated. This result confirmed that the chamber walls were responsible for reflections causing the measured field values and theoretical phase difference between the incident and reflected waves for the ferrite tiles is 90 degrees at 90 MHz accounting for the elimination of the reflections.<>