For electromagnetic applications, the absorbing material is made to attenuate the reflected component of an electromagnetic incident wave upon it. The priority need is to be able to have a region of space with no reflections so as to keep the field constant.

The absorbent materials used in anechoic chambers are:

• ferrite panels for coverage in low frequencies that convert incident wave energy into heat energy
• pyramidal absorbers made of rigid or expanded material (polyurethane foam) impregnated with carbon or colloidal graphite.

The internal arrangement, shape of the absorbing material and internal media require careful study of wave propagation within the anechoic chamber. These characteristics, together with those of the cone material, greatly influence the attenuation performance of reflected and incident waves.

The entire environment of the anechoic chamber is enclosed in a Faraday cage to screen out electromagnetic fields from outside that could nonrecurrently affect the "quiet zone," the radiated emission tests and thus on the measurements to be made. 

To verify the perfect functioning of the Faraday cage of the anechoic chamber, the shielding effectiveness is measured, which certifies the level of signal attenuation Inward and outward from the shielded chamber. 

The anechoic chamber, located in our laboratory, is 6 by 4 meters in size and covers a measurement range from 200 MHz to 40 GHz. In this environment we can characterize radiation diagrams of antennas, perform calibration of electric and magnetic field sensors. The MPB's anechoic chamber is also used for all measurements needed by our research and development department in the various stages of testing during the design of new measuring instruments.