Adamenko Y. Filtering devices based on apodized electromagnetic crystals

The limiting factors of electromagnetic crystals (EC) efficiency and the use of apodization for creating highselective EC are analyzed in thesis. Designed impedance modeling approach of EC and EC models provide visibility of structure-characteristics connection needed for productive design of EC devices. Proposed and investigated the combined bulk inhomogeneities compared to typical EC-inhomogeneities increase the maximum value of wave impedance from about 200 ohms to 550 ohms. Modifications of these inhomogeneities with increased phase length providing improvement of effective permittivity from 1.5 to 12, which corresponds to the reduction in the size of EC, calculated for a given frequency. The features typical EC apodization are analyzed, the apodization principles generalization in natural and man-made structures are done, which allowed to develop the methods of structural (amplitude, phase, edge) apodization of EC and the new one (adaptive and impedance). EC based on combined inhomogeneity allow to create high band selectivity in a small number of inhomogeneities. Experimental research of highselectivity EC layout based on the proposed combined inhomogeneities confirmed the achievement of the highest values of EC parameters in five irregularities: attenuation 62 dB at frequency 3.49 GHz with a relative bandwidth of 85%. Impedance ratio of dissimilar EC areas equals 17.5. Proposed and investigated compact narrowband filter based on the combined EC inhomogeneities with impedance apodization gives quality factor in 36.1 with a bandwidth at 3 dB level equals 87 MHz and with loss 2.6 dB.