Criteria of crystal-like structures approaching by impedance delta-inhomogeneities lattices

Introduction. Crystal-like structures (CS) have unique, similar to crystals, band spectral characteristics and form the basis of new various signal processing devices. In this paper the criteria of CS approaching by delta-inhomogeneities lattices are established. Wave mediums of crystal-like structures. Quantum-mechanical, electromagnetic and acoustic wave mediums are considered and expressions for impedance delta-barriers and delta-wells input impedances and admittance are described. Unlimited impedance delta-wells lattices. Features of impedance delta-wells lattice are considered. Expression for input impedance of impedance delta-wells lattice is obtained. Active and reactive input impedance components characteristics of unlimited impedance delta-inhomogeneities lattices are presented. Unlimited crystal-like structures approaching. Comparative analysis of input impedance components characteristics of unlimited CSs and delta-inhomogeneities lattices are considered. Criteria of unlimited CSs approaching by delta-inhomogeneities lattices are established. Limited crystal-like structures approaching. Comparative analysis of input impedance components characteristics of limited CSs and delta-inhomogeneities lattices are considered. Criteria of limited CSs approaching by delta-inhomogeneities lattices are established. Conclusions. Criteria for unlimited and limited CS approaching by delta-inhomogeneities lattices limiting CS inhomogeneity width by one-fourth of the wavelength and normalized wave impedance of electromagnetic and acoustic inhomogeneities by values of not less than 3 or not more than 1/3. These criteria determine range of modeling - energy for quantum-mechanical CSs and frequency for electromagnetic and acoustic CSs accordingly.