以耦合共振器實現小型化環形耦合器之設計

Abstract

本篇論文提出了數種利用耦合共振網路來實現的微小化環形耦合器。傳統環形耦合器所需的四分之一波長及四分之三波長傳輸線可以利用共振器之間的電耦合及磁耦合來加以取代。因此，傳統的環形耦合器可以轉變成一個耦合共振器網路。由於使用耦合共振器網路的架構，能量傳遞主要發生在共振器的共振頻率，所以使用這種方法合成的環形耦合器會具有帶通的特性。另一方面，耦合器的面積也會隨著共振器的縮小而減少。 為了小型化的需求，本論文提出了一利用彎折的四分之一波長共振器組成的環形耦合器，其面積只佔傳統耦合器的7%。此外，為了加強止帶的阻拒效能，具有控制諧波功能的網狀共振器被引入到耦合器的設計之中。所實現的環形耦合器面積只佔傳統耦合器的16.8%，同時具有30dB的止帶阻拒上至4.3倍的耦合器操作頻率。

This thesis presents several miniaturized rat-race couplers with coupled-resonator network. The -line and -line sections of conventional rat-race coupler can be replaced with electric and magnetic coupling between resonators due to the opposite phase responses of electric and magnetic coupling. Therefore, the conventional rat-race coupler can be transformed into a coupled-resonator network. As a result of the coupled-resonator configuration, power transmission mainly occurs at the common resonant frequencies of the resonators. Therefore, bandpass response can be achieved in this topology. On the other hand, the dimension of coupler can be reduced as the size of resonator becomes smaller. For miniaturization, a rat-race coupler with meandered quarter-wavelength resonators is proposed in this thesis. The implemented coupler only occupies 7% circuit size of the conventional one. Furthermore, to enhance stopband performance, compact net-type resonator with controllable harmonics is introduced. By utilizing compact net-type resonators, the proposed rat-race coupler occupies 16.8% circuit size of the conventional design, while the rejection level in the stopband is better than 30dB up to 4.3f0.