Semi-Anechoic Chambers

What is a semi-anechoic chamber?
A semi-anechoic chamber is a shielded enclosure lined with RF absorber on the walls and ceiling, combined with a conductive, reflective ground plane across the floor. This configuration recreates the measurement conditions of an Open Area Test Site (OATS) — the reference environment on which international radiated emissions standards are based — while keeping your testing indoors, controlled and free from external interference.

How it differs from a fully anechoic chamber
The difference comes down to the floor. A semi-anechoic chamber retains a reflective metal ground plane, deliberately preserving the ground reflection that forms part of the standardised measurement geometry for compliance testing. A fully anechoic chamber, by contrast, is lined with absorber on all six surfaces — including the floor — to eliminate reflections entirely and simulate true free-space conditions.
That makes each suited to a different job. Semi-anechoic chambers are the established choice for radiated emissions compliance testing to standards such as CISPR 16 and EN 55032, where the ground reflection must be present. Fully anechoic chambers suit free-space measurements and immunity work where any reflection would distort the result.