Radiation-absorbent material

In materials science, radiation-absorbent material (RAM) is a material which has been specially designed and shaped to absorb incident radio frequency (RF) radiation (also known as non-ionising radiation), as effectively as possible, from as many incident directions as possible. The more effective the RAM, the lower the resulting level of reflected RF radiation. Many measurements in electromagnetic compatibility (EMC) and antenna radiation patterns require that spurious signals arising from the test setup, including reflections, are negligible to avoid the risk of causing measurement errors and ambiguities. RAM are widely used in RF anechoic chambers to achieve an "echo-free" environment.