| Summary: | 碩士 === 國立臺灣大學 === 電信工程學研究所 === 102 === This thesis proposes new design concepts for millimeter-wave filters and triplexers based on SIW (substrate integrated waveguide) structures. The first part designs two variations of a two-in-one bandpass filter, implemented on LTCC (Low Temperature Co-fired Ceramics). The second part designs a triplexer without matching network that is realizable on millimeter-wave frequency, and is implemented on circuit boards.
The design concept in the first part is to combine two filters using common resonators into a single two-in-one bandpass filter circuit. This part utilizes the concept of modal orthogonality in the SIW cavities by letting different modes control filter responses in different paths. Therefore, coupling coefficients of each mode between adjacent cavities may be controlled independently through proper locations of the coupling slots. Also, a port may only excite one of the modes with a proper feeding position. In order for the four port integrated circuit to have two independent filter response paths, good isolation between the filter responses must be maintained. Each response is controlled by one of the two orthogonal modes used, therefore, the position of the feeding slot is crucial in keeping the modes orthogonal. The two-in one bandpass filter achieves 32.6 % circuit area miniaturization by providing an additional filter response path using the same amount of cavities of a single bandpass filter.
The second part proposes a triplexer design that is realizable in millimeter-wave frequency. The design concept is to use the distributed coupling technique to rearrange the three SIW filters along the feeding line. Each filter may share the common feeding line due to different magnitudes of the magnetic field at different frequencies, therefore the matching network is unnecessary for this design. This triplexer achieves good insertion loss, isolation greater than 24 dB, and has a high freedom in choosing passband frequencies.
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