I've asked several related questions, but I'm afraid that some of the answers that I received, while great answers, might be skewed because of incorrect assumptions or unclarity in my questions.
The answer to this question seems to indicate that any good conductor provides good shielding of both the E and H components of far-field EMR, because the fields are mutually dependent on one another for their existence. The up votes would indicate a reliable answer. But answers that I've received to some of my questions have left me with doubts. So, I'll ask a different way:
Given a box that has continuous, conductive, metallic walls with no gaps, and air at its exterior and interior, when a plane wave hits the box from the outside, are the E and H fields attenuated equally? Or, are there wall material properties that could cause EMR to emerge in the near field at the inner surface of the walls with E or H field dominant? For example, could a sealed enclosure provide good electric shielding and poor magnetic shielding of plane waves? Specifically, is thicker or higher-permeability material required to shield the H component of a plane wave at 500 MHz than is required at 1 GHz? Or, are considerations of thickness and permeability applicable only when shielding near-field AC magnetic fields or far-field EMR at frequencies below hundreds of kHz? Please assume that the box is sized such that all ingress radiation is in the near field.
Further, when I look at electromagnetic shielding equations and explanations thereof, I see no mention of field strength. A fairly well-known engineer assured me early on in my project that with attenuation in the neighborhood of 50 to 80 dB, field strength is not an issue, even under EMP conditions. Yet intuitively, I suspect that a pulse of 50 kV/m and 133 A/m would present unique challenges. So, how well will an enclosure whose walls contain less than 3 microns of metal with milliohmns of surface resistance stand up under an EMP? If your answer includes calculus equations, please include a brief explanation of the equations.