Shield Efficiency

Attenuation Chart For RF Meter Shield Model SX1000418

Attenuation is one of the principal indicators for measuring the effectiveness of electromagnetic interference shielding. It refers to the difference between an electromagnetic signal’s intensity before shielding and its intensity after shielding. Attenuation is marked in decibels (dB) that correspond to the ratio between field strength with and without the presence of a protective medium. The decrease in a signal’s intensity, or amplitude, is usually exponential with distance, while the decibel range falls along a logarithmic scale. This means that an attenuation rating of 50 dB indicates a shielding strength ten times that of 40 dB. In general, a shielding range of 10 to 30 dB provides the lowest effective level of shielding, while anything below that range can be considered little or no shielding. Shielding between 60 and 90 dB may be considered a high level of protection, while 90 to 120 dB is exceptional.