This paper presents a method to construct composite right/left-handed transmission line using coupled lines. A general procedure to design a composite right/left-handed unit cell is presented. The procedure was used on a specific coupled line configuration, which is the coupled microstrip lines with slotted ground. It is shown that by proper design of the slotted ground, the coupling between the two microstrip lines can be increased dramatically keeping practical dimensions for the coupled line width and spacing. Moreover, with accurate slotted ground design, equal even and odd electrical lengths can be achieved. The performance of this composite right/left-handed line, which is characterized by backward waves with phase advance, is demonstrated by both simulated and measured results and they show good agreement. The realized composite right/left-handed transmission line has a broad bandwidth and small size.
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