Frequency Selective Surface for EM Shielding

Hi, I am interested in Frequency Selective Surface (FSS) for EM Shielding applications. FSS is best suitable for enclosures of small size (< 50cm ), which i have designed and tested. But when tried FSS for enclosures of big size enclosure resonance dominates and FSS become useless. Can anybody help. Thanks.

Frequency-selective surfaces are used for frequency-selective reflective components. For EM shielding you need good absorbers (some are designed for certain frequency bands) and elastic conductive inserts to prevent leakage from enclosures.

Did you mean placing absorbers inside the enclosures to reduce the resonance effect.

I mean exactly what I wrote: frequency selective surfaces are used as reflectors. Suppressing resonance in cavities is done by absorbers, not by FSSs.