The influence of various types of distortion of periodicity on the eigen parameters of the layered Bragg resonators is analyzed. The conditions for the reduction of the quality factor of unwanted side Bragg oscillations in quasiperiodic apodized resonators are determined. It proposes the construction of periodic and quasiperiodic structures and apodized Bragg resonators with thin contrast layers, which are relatively easy to technologically implement in the microwave range.
Complex eigenfrequencies of periodic and quasiperiodic Bragg structures. Logarithm of transmission coefficient of double quasiperiodic Bragg resonator.
Complex eigen values of real part frequency and imaginary part of permittivity. Bragg structures. Logarithm of transmission coefficient of periodic and quasiperiodic Bragg resonators with one active of two abnormal layers.
The perturbation of parameter of periodical Bragg structure is a flexible tool to obtain the desired reflection and transmission characteristics. Apodization of Bragg reflectors leads to significant reduction of side lobes, while the main maximum is expanding, and its amplitude decreases slightly.
The minimum level of the first sidelobe can be obtained when the apodized function is as smooth as possible. The influence of apodization on the eigenfrequencies of structure increases with growing the distance between the frequency of the Bragg reflections and eigenfrequency. With the introduction of the violation of the structure periodicity as a double thickness of the central layer, there are conditions for the appearance of a high quality oscillation in the Bragg reflection band. Under the apodization of Bragg resonators the frequency selectivity increases due to the relative decrease of the resonances quality factor for the side resonance frequencies subject to the condition that an average contrast throughout the thickness of the structure saves its value.
Languages: Matlab
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