寬頻微波耦合器與濾波器

Abstract

本篇論文包含兩類微波電路分別是小型化的超寬頻90度 3dB的耦合器和多層寬頻帶通濾波器。 首先採用5節對稱式串接的共平面波導架構來實現超寬頻(2-18GHz) 90度 3dB的耦合器，並利用垂直安裝平面(VIP)基板來達到中心節強耦合的需求，還補償了中心節奇偶模相位速度不相等的問題，最後實作電路採用高電介質的母基板(er=9.8)來達到小型化的電路尺寸(16 .8mm×6 mm)。 寬頻(2-4GHz)帶通濾波器則是利用平行耦合的步階阻抗諧振器來達成，步階阻抗諧振器(SIR)有兩個優點，分別是有效減小諧振器的長度達到縮小化和抑制上止帶高階模的干擾，最後利用多層結構來達到強耦合並實現中心頻3GHz、比例頻寬66.67%和高止帶抑制的帶通濾波器。

The thesis includes the two kinds of microwave circuits, namely the miniaturized ultra-broadband quadrature hybrid coupler and the multilayer wideband bandpass filter. We adopt a 5-section symmetrical cascaded coplanar waveguide (CPW) structure to realize the ultra-broadband (2-18GHz) quadrature hybrid coupler. In the tightest center coupling section, we propose the vertically installed planar (VIP) structure to achieve it and also compensate the unequal odd- and even-mode phase velocities. The fabricated circuit size miniaturized by high dielectric substrate (er=9.8) is 16.8 mm×6 mm. Then, a wideband (2-4GHz) bandpass filter is designed by using parallel coupled line stepped impedance resonators (SIR). The properties of SIR can reduce the resonant length and suppress the upper stopband interference. Furthermore, we propose multilayer structure to obtain the tight-coupling. Finally, a wideband filter with center frequency at 3 GHz, 66.67% fractional bandwidth, and high stopband rejection is presented.