Electromagnetically transparent metamaterial

An electromagnetically transparent metamaterial, comprising a substrate and a plurality of man-made metal microstructures arranged periodically inside the substrate, wherein each of the man-made metal microstructures is equivalent to a three-dimensional (3D) circuit formed by three identical 2D circuits that are perpendicular to one another at a common midpoint, each of the 2D circuits comprises an inductor branch and two identical capacitor branches that are symmetrically connected in parallel with the inductor branch, the three inductor branches having a common intersection point and perpendicular to one another form three axes of the 3D circuit, and the 3D circuit is associated with a waveband so that both a dielectric constant and a magnetic permeability of the metamaterial are substantially 1 within the waveband, wherein each of the man-made metal microstructures comprises:

• a first metal branch, a second metal branch and a third metal branch intersecting with one another at a common midpoint;
• two fourth metal branches, which have midpoints located at two ends of the second metal branch respectively and which have the same length as and are parallel with the first metal branch;
• two fifth metal branches, which have midpoints located at two ends of the third metal branch respectively and which have the same length as and are parallel with the first metal branch;
• two sixth metal branches, which have midpoints located at two ends of the first metal branch respectively and which have the same length as and are parallel with the second metal branch;
• two seventh metal branches, which have midpoints located at the two ends of the third metal branch respectively and which have the same length as and are parallel with the second metal branch;
• two eighth metal branches, which have midpoints located at the two ends of the second metal branch respectively and which have the same length as and are parallel with the third metal branch;
• and two ninth metal branches, which have midpoints located at the two ends of the first metal branch respectively and which have the same length as and are parallel with the third metal branch, the two seventh metal branches and the two eighth metal branches are positioned on a first plane of the man-made metal microstructure, the two fifth metal branches and the two ninth metal branches are positioned on a second plane of the man-made metal microstructure, the two fourth metal branches and the two sixth metal branches are positioned on a third plane of the man-made metal microstructure, each of the seventh metal branches and each of the eighth metal branches have at least one pair of first notch structures disposed symmetrically with respect to their respective midpoints or each of the seventh metal branches and each of the eighth metal branches are formed with the first notch structure at their respective midpoints;
• and each of the fourth metal branches and each of the fifth metal branches have at least one pair of second notch structures disposed symmetrically with respect to their respective midpoints or each of the fourth metal branches and each of the fifth metal branches are formed with the second notch structure at their respective midpoints.