A new protection method using an energy selective surface（ESS）is presented for protecting electronic equipments from attacking by high power electromagnetic weapons.ESS is an impedance surface that is sensitive to the incident electromagnetic field intensity.The protection mechanism

structural design

equivalent circuit modeling

and full-wave simulations of ESS are discussed.Theoretical analysis and simulation results show that ESS is transparent to small signals but opaque to larger signals.The typical insertion loss of ESS is about 1.5 dB and the minimum shielding efficiency is about 20.0 dB in the L band.ESS with the variable transmission loss can be used for protecting electronic equipments from damage in intensive electromagnetic environments.