| Summary: | 碩士 === 華梵大學 === 電子工程學系碩士班 === 106 === This paper proposes the use of two sets of three-stage coupled-line structures on a three-layer FR4 printed circuit board (PCB) to design RF components using in wireless communication systems, capable to separation and combination of center frequency 2.5 GHz low band and center frequency 5.5 GHz high band transmission signal from the antenna and RF IC. The two sets of coupled lines are arranged in appropriate intervals, the low frequency circuit and the high frequency circuit are individually added three capacitors π-type circuit to become a coupled line structures. In the π-type circuit, the bridged capacitor is mainly used to adjust the coupling strength. And in the end of the first segment of each frequency band circuit, it is connected to the grounding capacitor respectively, the purpose is to use the LC resonance principle to shorten the length of the line and achieve impedance matching at the same time. A matching circuit that connects high and low frequencies in series is using a transmission line for matching. The RF diplexer using the cascade coupling structures with transmission line matching embedded circuit size of 30 mm x 20 mm x 0.64 mm (length x width x height).
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