An anechoic chamber is a RF protected room which walls and roof have been secured with Radiation Absorbent Material (RAM) that spreads or absorbs such a large amount of the incident energy that it can simulate free space. An anechoic chamber is simulating an Open Area Test Site (OATS), without interference from environmental electromagnetic field pollution.  Testing can be conducted on full-scale objects including different electronic devices, vehicles, aircraft, spacecraft, or on scale models where the measurement radiation wavelength radiation is scaled in direct proportion to the target size.

An Anechoic chamber is utilized to measure antenna characterization, electromagnetic interference (EMI), and electromagnetic compatibility (EMC). Inside the chamber are absorbers that are designed with a variety of pyramidal items that steer the propagating incident field onto their neighboring absorbers.  The chamber makes a virtual infinite space that has practically no interior reflections and will be safe from all undesirable external RF noises, by absorbing electromagnetic waves inside the chamber and hindering approaching signals from outside.

An anechoic chamber is a space that totally wipes out external noise so extremely exact measurements can be taken utilizing calibrated laboratory equipment. Originally these were intended for audible noise but the principles are the same for radio wavelengths .an EMI/EMC anechoic chamber suggests a significant investment. Various detailed considerations must be weighted in an anechoic chamber project. The screened room should be built to provide an atmosphere free of extraneous signals.

Anechoic chambers are categorized as "Semi Anechoic Chamber" or "Fully Anechoic Chamber", where latter has absorbers on every internal surface of the chamber.