| Summary: | 碩士 === 國立交通大學 === 電信工程研究所 === 84 === In this thesis we propose and analyze a partially sealed
absorbing cavity in a packaged microstrip circuit. This
structure is formed by absorbing dielectric layers attached on
the top cover of the packaged microstrip circuit and sandwiched
by two metal diaphragms. Any device which tends to excite
higher-order modes (parasitic modes) may be designed inside this
cavity so that the excited higher-order modes are confined by
the diaphragms and decayed by the absorbing layers. The method
of lines coupled with the mode-matching method will be adopted
to investigate this structure. The coupling effect, with respect
to the microstrip dominant mode and higher-order modes, of two
metal diaphragms will first be analyzed, and then the
influences, on the characteristics of the cavity, of varying the
position, width, and depth of the absorbing layers and the
distance between the diaphragms will be investigated.
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