【正文】 印出的結(jié)果可參考底下所列印出的形式。頁數(shù)各工作項目 (或子項目 )以 10 頁為原則。圖表，下接其說明，但可置於文中或文後。 2 Analysis of Planar Transitions ChunHsiung Chen, YoShen Lin, and ChihWai Kao ABSTRACT Novel uniplanar 180o hybridring couplers consisting of coplanarwaveguide (CPW) rings and spiraltype phase inverters are proposed. In this study, CPW phase inverters with singlespiral and twinspiral type slotline short stubs are utilized to design the hybridring couplers. Specifically, two hybridring couplers with 33% (singlespiral type) and 40% (twinspiral type) bandwidths are implemented and examined, theoretically and experimentally. Keywords – Spiraltype phase inverter, 180o hybridring coupler. INTRODUCTION Hybridring couplers are fundamental ponents of microwave circuits such as balanced mixers, phase shifters, and feed works in antenna arrays. The ratrace hybridring coupler is the most mon one, but its area is undesirably large and its bandwidth is also limited due to the use of a 4/3g? line segment. In recent years, uniplanar transmission lines such as coplanar waveguide(CPW), slotline, and coplanar stripline are widely used in microwave integrated circuit(MIC) and monolithic microwave integrated circuit(MMIC). Uniplanar lines have the merits such as easy realization of shortcircuit end, no need for via holes, low dispersion, and easy integration with active ponents or lump elements. Using uniplanar line 3 structures, several 180o hybridring couplers have been reported [1][3]. In those papers, suitable wideband open circuits have been properly incorporated in the hybrid design, since the bandwidth of a hybrid is mainly determined by the performance of these open circuits. The simplest open circuit structure is the quarterwavelength shortcircuit stub, but its bandwidth is quite limited. To improve the bandwidth, some modified structures have been proposed, such as to use the twin short stubs or radial stubs [4][5], but their sizes are still large. Recently, a twinspiral slotline shortstub structure was proposed to reduce the size of CPWtoslotline transition [6]. Based on the same idea, novel ?180 hybridring couplers with singlespiral and twinspiral type phase inverters are proposed and carefully examined. These