Field uniformity of a semi-anechoic chamber

This article describes work performed by Radio Frequency Investigation Ltd, to investigate the uniformity of the field strength over a 1 m3 volume within a semi-anechoic chamber. The investigation was performed over the frequency range 30 MHz to 1000 MHz. Methods of improving the field uniformity using additional blocks of absorber within the chamber were also studied. The results demonstrate that a semi-anechoic chamber alone does not provide a sufficiently damped environment to achieve a field uniformity of ±3 dB within the test volume. Using additional blocks of absorber within the chamber it was possible to substantially improve the field uniformity, however it was still outside the ±3 dB tolerance. Overall, the results illustrate that although it may be possible to achieve a field uniformity of ±3 dB over the test volume, further investigation into the amount and placement of additional absorber will be required. Reprinted from the Proceedings of Euro EMC Electromagnetic Compatibility Conference at Sandown Exhibition Centre, October 1992 by kind permission of Reed Exhibition Cos (UK) who have announced the 1993 Euro EMC, 5-7 October at Sandown Centre.