2D Periodic Structure for Acoustic and Electromagnetic Radiation

Аннотация

The propagation of microwaves in the frequency range from 8.5 to 12GHz and acoustic radiation in the frequency range from 8.5 to 14 kHz in the same 2D periodic crystal formed by cylindrical spiral coils has been investigated. The frequency ranges in which the effective refractive index n_ef of the crystal is close to zero are found. In these ranges, microwaves are collimated and concentrated in a narrow lobe with an FWHM of about 9◦. Focusing of divergent microwave and acoustic beams by a flat periodic structure has been observed in the frequency range where the effective refractive index of this structure is negative.