Low frequency range cavity resonance elastomer absorber
Construction consists of a conductive coating ""lossy"" fabric, separated from a conductive ground plane by a low dielectric foam core. As a tuned (narrowband) absorber, the material must have an electrical thickness of 1/4 of a wavelength at the frequency of operation. This promotes signal attenuation by both energy dissipation within the ""lossy"" fabric material, as well as cancellation of the incoming and emerging signals at the surface, where they are 180 degrees out of phase. Through accurate control of the coating process used for the ""lossy"" fabric, absorption levels of greater than 20dB are easily and consistently achieved with a 10% bandwidth at the specified operating frequency.