Isotropic Epsilon-Negative Particles

This paper presents two particles with negative permittivity in some frequency band. The response of a single dipole loaded by an inductance is strongly anisotropic. The response of a spider dipole does not depend on the orientation of the electric field of a wave being incident perpendicular to the particle substrate. These two particles are used in designing an isotropic epsilon-negative metamaterial. A unit cell of the metamaterial consists of a cube bearing the proposed particles on its faces, located with specific orientations. The experiments showed that only the single inductively loaded dipole is suitable for manufacturing of an isotropic epsilon-negative metamaterial. The isotropy of the new particles was checked by measurements.