A Transparent Metasurface Supporting Pseudoanapole by Mirroring Split-Ring Resonators

This letter explores a novel possibility to create a transparent metasurface without any size modulation scheme, simply by mirroring split-ring resonators (SRRs). With this technique, a pseudoanapole state can be formed, where all major multipoles can be nullified, forming a transparency window with full transmission. In the mirrored SRR, magnetic dipoles are induced at the center of each SRR with antiphase components, thus forming the so-called toroidal dipole. The toroidal dipole constitutes a separate higher order moment whose destructive interference with the fundamental electric dipole moment forms the so-called anapole mode. However, under the
$H_{||}$
excitation scenario, a pseudoanapole state can be excited, demonstrated by using the multipole scattering expansion to find the first resonant dipoles of the metasurface (electric dipole, toroidal dipole, magnetic dipole, and quadrupole). Theoretical results are experimentally validated using microwave measurements in an anechoic chamber facility.