| Summary: | 碩士 === 國立彰化師範大學 === 工業教育學系 === 89 === In this research, a rigorous volume integral equation approach is employed to analyze the guidance and leakage properties of dielectric strip waveguides with rectangular and trapezoidal cross-sections, including single and coupled waveguide structures. For analysis, the spectral Green's function for the system integral equation is first derived. Then the cross-section of the dielectric strip waveguide will be divided into small cells for numerical process. By using the method of moments, a matrix equation for the waveguide system can be obtained, from which both the phase and attenuation constants are solved. We will focus on the investigation of the effects of the strip cross-section and material anisotropy on the dispersion behavior of the fundamental and the first two higher order modes. The influence of the strip separation and the surface-wave leakage on the coupling effect will also be studied.
Computed results show that for the anisotropic dielectric waveguide, variation of the x- (z-)component of the dielectric constant exhibits stronger effect on the dispersion characteristics of the Ex (Ez) modes. This is due to the fact that the Ex (Ez) mode has larger x- (z-)component of electric field. On the other hand, when the separation distance of the coupled guiding strips is increased, the phase constants of the even and odd modes tend to degenerate and converge to that of the corresponding isolated dielectric waveguide. For the attenuation constant, since the excited surface wave by each waveguide may add in phase or out of phase at certain separation to give a maximum or minimum leakage for the strip mode, it possesses an oscillatory behavior. For validation of this work, some simple dielectric waveguide structures were also calculated and compared with other researchers’ results; it was seen to have very good agreement.
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