CONTROLLED REFLECTIVE SURFACES BASED ON FERRITE LAYER

Subject and purpose. The subject of the research are the specific features of electromagnetic waves reflection from layered ferrite-metal and ferrite-dielectric structures with a ferrite layer of subwavelength thickness. The purpose of the work is to study the possibilities of controlling the amplitude, phase and polarization characteristics of electromagnetic waves reflected from layered structures containing ferrite.

Method and methodology. The analysis of electromagnetic wave complex reflection coefficient for electromagnetic waves reflected from ferrite layers on metal and dielectric was carried out using the method of scalar permeability. The model of circularly polarized T-waves and transmission line theory were applied.

Results. The frequency and field dependences of the reflection coefficients’ absolute values and phases for electromagnetic waves reflected from semi-infinite ferrite and ferrite layers on metal or dielectric were theoretically investigated. An analytical formula for the skin depth in a normally-magnetized ferrite for a larmor wave is obtained. Theoretical estimates for the reflected waves phase tuning near the ferromagnetic antiresonance frequency for a layer of polycrystalline iron-yttrium garnet, covering the metal, are given. The field dependences of the of HE+11d and та HE–11d modes resonant frequencies of cylindrical cavity resonator with the ferrite-metal structure at the end face have been experimentally investigated.

Conclusion. The frequency and field dependences of the absolute values and phases of the complex coefficient of reflection from the ferrite medium and ferrite layer on the metal or dielectric for a circularly polarized incident electromagnetic wave are studied and possibility of the reflected waves amplitudes and phases control is demonstrated. The possibility of using a theoretical model for the reflection coefficient phase tuning, due to the magnetic field, for an electromagnetic wave reflected from a ferrite layer on a metal was experimentally verified, using the example of frequency tuning of the HE±11d modes of a cylindrical cavity resonator with a ferrite-metal structure at the end face. The gradient distribution of the phase of coefficient of reflection from reflective surface was proposed as a way to control the direction of propagation of the reflected wave.