“…In a different field of metamaterials, a novel counterintuitive resonant phenomenon, named supercoupling, based on resonant transmission, tunneling, and energy squeezing through subwavelength narrow channels has been recently introduced and developed by employing metamaterials with near-zero permittivity [11][12][13][14][15][16][17]. In [12][13][14][15][16], moreover, it was shown that similar energy squeezing may be achieved in hollow waveguide channels near their cutoff frequencies, demonstrating how the tunneling mechanism described in [11] may conceptually be obtained in a simple microwave waveguide at its cutoff, which may behave effectively as an "-near-zero metamaterial with ''infinite'' phase velocity.…”