▎ 摘　　要

NOVELTY - The device has a set of slabs of which permittivity is periodically changed over time and which has a predetermined thickness, where the slabs are arranged at regular intervals. A material included in the slab is different according to a frequency band, when the frequency band is a microwave band, the slab having a metamaterial, and the slab has a low temperature gallium arsenic (LT-GaAs) or graphene. A distance (or a gap) between two adjacent slabs is shorter than an incident wavelength and a wavelength (speed of light/fm) based on a permitivity change period. USE - Parametric device for use as frequency converter and oscillator for use in parametric system. ADVANTAGE - The parametric device converts and amplifies an electromagnetic wave in a wavelength band in which it is difficult to expect frequency conversion and amplified oscillation. The user is capable of designing amplification efficiency when the parameter device operates as an oscillator. The electromagnetic wave growing rate is controlled according to time according to a purpose. The directional electromagnetic wave device allows a user to arbitrarily designate a propagation direction of the electromagnetic wave. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a parametric system. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of a parametric device.