Design and evaluation of the RF anechoic chamber at HSD

Work carried out during various stages of design, construction, and evaluation of RF screened, anechoic 18.3 x 7.3 x 7.3 m rectangular chamber at HSD Stevenage is described. Results are presented of the reflectivity for the 3 cu m and 3 x 2.5 x 2.5 m volumes of the quiet zone. The design of this RF anechoic facility followed four distinct phases of experimental work, during which three different distributions of the anechoic material were investigated, together with the 1/6th scale physical modelling. The optimum configuration finally selected consists of a uniform distribution of 0.9 m pyramids on two sides, floor and ceiling, and 1.8 m material on the two end walls. At the end remote from the quiet zone there is an additional 4.3 m wide band of absorbing material backing onto the uniform pyramids. The feature of this facility is the relatively good performance over a 3 cu m quiet zone at low frequencies.