A rectangular RF anechoic chamber, where the material or absorbing material attached to its feeding wall has a homogeneous property on X-Y plane, i.e. the plane parallel to the feeding wall. The MA(s) are mounted on the feeding wall from which the material with a homogeneous property will reduce interferences from the fields which produce scattered fields from the wall; and may produce a quiet zone with significantly improved quality, and specially at low frequency band. Quiet zone quality means the field uniformity in the test zone.