We design a terahertz metamaterial composed of metal-dielectric-metal, which consists of metallic layers with an air hole array and one coaxial closed ring resonator in the air hole.

We have provided an explanation of the transmission characteristics by means of the surface plasmon polaritons (SPPs) and magnetic polaritons (MP) resonance based on the distribution of the surface current.

The equivalent LC circuit models of the structure are set up based on the MP resonances.

The effects of the geometric parameters on the transmission peaks are studied by the equivalent LC circuit models.