Radiation suppression ratio measurement of noise suppression sheet by compact 3m method

A noise suppression sheet (NSS) is used for decoupling of the noise path, suppressing RF noise current, and reducing radiation. A microstrip line (MSL) test fixture is also used for measuring the radiation suppression ratio (Rrs) [1] as the antenna. The ratio is derived from a comparison before and after the NSS installation in accordance with CLSPR22, the 3m or 10m test method in an anechoic chamber, or an open-area test site. A new method for determining the Rrs that can replace the 3m and 10m test methods is described here. This new compact 3m method involves the use of a NSS sample, dielectric lens, receiving antenna, and network analyzer. The features of this method are as follows: 1) there is no anechoic chamber, 2) it is compact, 3) it is easy to change the sample because of the vertical system design, and 4) it requires no power amplifier or low noise amplifier because the EM wave is not spread.