An anechoic chamber is a room in which there are no
echoes. This description was originally used in the context of
acoustic (
sound) echoes caused by
reflections from the internal surfaces of the room but more recently the same description has been adopted for the
radio frequency (RF) anechoic chamber. An RF anechoic chamber is designed to suppress the
electromagnetic wave analogy of echoes:
reflected electromagnetic waves, again from the internal surfaces. Both types of chamber are normally constructed, not only with echo suppression features, but also with effective isolation from the acoustic or RF
noise present in the external
environment. In a well designed acoustic or RF anechoic chamber, the equipment under test will only receive signals (whether acoustic or RF) which were emitted directly from the signal source, and not reflected from another part of the chamber.
See more at Wikipedia.org...