A Miniaturized Branch-Line Coupler Using Triangular Patch Type Artificial Transmission Line

초록

A branch-line coupler using microstrip artificial transmission lines (ATLs) with slotted triangular patches is proposed. For the ATL, a five-section stepped-impedance line (SIL) is compactly folded into a right angle isosceles triangle, and the effect of the slot width between folded lines is analyzed. The designed branch-line coupler is composed of four ATLs, so that it has a maximally compact rectangular geometry. A further miniaturization by changing patch shape and the performance analysis according to the slot widths between the four ATLs are carried out. The fabricated 3-dB branch-line coupler has comparable electrical performance and only 10.9% area compared to the conventional branch-line coupler at 0.717 GHz, which is one of the smallest couplers among similar studies that have been reported. (c) 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1718-1721, 2013

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