1. A method for manufacturing a panel for a reflective broadband electromagnetic shield, the method comprising the steps of:(a) forming a core of substantially the same size and same shape as the panel, the core having first and second surfaces on opposite sides thereof with the distance between the first and second surfaces defining a thickness of the core;
(b) building a layered, reflective broadband electromagnetic shielding cover having a thickness substantially less than the thickness of the core, wherein the step of building comprises the steps of:
forming metal into a porous first stratum exhibiting pronounced low-frequency electromagnetic shielding properties;
assembling electrically-conductive elements into a second stratum exhibiting pronounced high-frequency electromagnetic shielding properties; and
securing the second stratum to the first stratum in an overlapping electrically-continuous relationship; and
(c) disposing the cover on the first surface of the core.