RF Anechoic Chamber

The RF anechoic chamber is the standard facility for antenna measurement and electromagnetic compatibility (EMC) testing at frequencies above 30 MHz. Unlike acoustic anechoic chambers — which absorb sound waves — RF anechoic chambers absorb electromagnetic waves using pyramidal or hybrid RF-absorbing foam tiles and contain the RF environment using a continuous copper or aluminium shielded room enclosure.

The HEMU Acoustics RF Anechoic Chamber combines our RF shielding construction (30–60 dB attenuation from 30 MHz to 40 GHz, selectable by specification) with ferrite-loaded polyurethane pyramid absorber tiles calibrated to the desired working frequency band. The absorber geometry and material composition are selected to achieve reflectivity better than −40 dB at the measurement frequency.

Chamber dimensions are engineered to meet the quiet zone (QZ) requirements specified in IEEE 149, CISPR 16-1-4, or customer-defined antenna range criteria. Standard far-field antenna measurement chambers provide a quiet zone diameter of λ×D²/λ (Rayleigh criterion) at the lowest test frequency. Compact range and near-field configurations are available for electrically large antenna systems.

The shielded enclosure uses welded modular steel panels with RF-gasketed doors, penetration panels for power, data, and fibre, and a pressure equalization port. Shielding effectiveness is verified by NSA 65-6 or MIL-STD-461 protocol at project commissioning. Acoustic isolation (STC 40) is integrated into the outer structural shell, providing a low-ambient-noise measurement environment for acoustic near-field analysis.