Recently, the scattering phenomena with RAM have been studied by both measurement and theoretical calculation. We measured RCS due to one flat layer RAM which was the basic pattern of flat layer RAM in order to clarify RCS characteristics. Owing to improve the high precision in measurements, the electromagnetic wave sneaking from the transmitting antenna to the receiving antenna can be decreased by means of putting RAM. As a result, we could confirm that two flat layers RAM absorbed electromagnetic wave 2.64 times larger than one flat layer RAM using the 3D electromagnetic simulation.