JRAT rubber sheet absorber: is a series of absorbers made of rubber filled with magnetic material. It is a resonant absorber from its absorbing principle. Flexible and thin thickness, JRAT can achieve an optimal absorbance in a narrow band. However, the band is still broader than those non-magnetic materials. The reflectivity at normal incidence could be up to -17 ~ -25 dB at the resonant frequency. And the relative frequency width is 24% and 35% separately for the reflectivity of -13dB and -10dB. Little change is caused by the 30 degrees incidence and -15dB for 45 degrees. As for 60 degrees, the vertical polarization is about -7dB and the horizontal polarization is about -13dB