Performance of subwavelength resonant cavities at FIR

A subwavelength 1-D resonator at FIR is presented and studied. The structure consists of a cavity formed between a metallised (silver) surface and a metamaterial surface comprising silver patches on a silver-backed silicon substrate. The concept derives from recent discoveries of artificial magnetic conductors. Full wave simulations, based on FEM and TLM methods, have been carried out to prove the concept and demonstrate the effective magnetic boundary condition. Further reduction of the cavity thickness to less than lambda/8 is presented. Significantly, the quality factor has been assessed as a function of the cavity profile. It is demonstrated that the quality factor drops to about one seventh of its value when the profile reduces from half to one eighth of the wavelength.