本研究採用基板合成波導技術實現兩個不同的雙工器，第一個電路是中心頻率為2.4/3/4.2/5 GHz的四通帶雙工器，透過兩個基板合成波導雙頻帶帶通濾波器並用T型微帶線接面組成的。首先，設計一中心頻率為3 GHz和5 GHz的雙頻帶帶通濾波器，其採用三角形四分之一模基板合成波導共振器並在上層金屬蝕刻微擾槽孔去設計，所使用的模態是TE101¬和TE202。其中，這些微擾槽孔可以控制TE202模態，同時不影響TE101模態，將原本共振頻率為6 GHz的TE202模態調整至5 GHz。另一個中心頻為2.4 GHz和4.2 GHz是採用四分之一模六邊形基板合成波導共振器設計，使用的模態為TE101和TE103，不使用前述三角形四分之一模共振器的方式設計是因為其高階模態會影響5 GHz的通帶。當兩個二階雙頻帶帶通濾波器皆設計完成之後，再用T型微帶線接面組合起來，經過微調和最佳化設計出四分之一模基板合成波導四通帶雙工器。第二個電路是透過半模六邊形基板合成波導作為第一級共振器，並使用TE102和Mode5的模態，中心頻設計在3 GHz和4 GHz的二階雙工器，而第二級共振器皆是使用四分之一模基板合成波導共振器以減少電路面積，透過六邊形共振器有別於傳統矩形共振器的電磁場分布，設計出具有良好隔離度且電路面積較小的雙工器。;This thesis introduces the application of substrate integrated waveguide (SIW) technology to implement two distinct diplexers. The first circuit is a quad-channel diplexer with center frequencies at 2.4/3/4.2/5 GHz. It consists of two QMSIW dual-band bandpass filters interconnected with a microstrip T-junction. Initially, dual-band bandpass filters are designed. A triangular QMSIW cavity with a centered 45-degree slot perturbation, which has center frequencies at 3 GHz and 5 GHz, is utilized for the design of the dual-band bandpass filter. The slot perturbation can control the resonance frequencies of TE202 mode without impacting the resonance frequencies of TE101 mode, allowing for the adjustment of TE202 resonance frequencies from the original 6 GHz to 5 GHz. The other dual-band bandpass filter with center frequencies at 2.4 GHz and 4.2 GHz is implemented using a quarter-mode hexagonal SIW cavity, utilizing TE101 and TE103 modes. The reason for not using the triangular quarter-mode cavity for the 2.4/4.2 GHz dual-band bandpass filter is due to the interference of its higher-order mode with the passband at 5 GHz. Once both dual-band bandpass filters are designed, they are combined using a microstrip T-junction and further optimized to achieve a QMSIW quad-channel diplexer. The second circuit involves the utilization of a half-mode hexagonal SIW cavity as the first-order resonant cavity for designing second-order diplexers. The resonance frequencies of TE102 and mode 5 are at 3 GHz and 4 GHz, respectively. Quarter-mode SIW resonators are employed in all second-order resonant cavities to minimize circuit area. The distinctive electrical and magnetic field distributions of hexagonal cavities, compared to conventional rectangular ones, are exploited to design diplexers with superior isolation performance.
