GENERALIZED IMPEDANCE-TRANSFORMING DUAL-BAND BRANCH-LINE COUPLERS FOR ARBITRARY COUPLING LEVELS

• DOI: 10.2528/pierb13061717
• Publication Date: 2014-01-14T06:33:42Z
• Authors: Qiang Liu; Yuanan Liu; Yongle Wu; Jun-Yu Shen; Shulan Li; Cuiping Yu; Ming Su
• Keywords: Line (geometry); Multi-band device

High-performance dual-band Doherty power amplifler and non-uniform circularly polarized antenna array require impedance- transforming unequal 90 - branch-line couplers for dividing phase shifting in the feed networks. In this paper, an analytical design methodology of generalized impedance-transforming arbitrary coupling levels is proposed. The coupler features wide range realizable frequency ratio, multiple ∞exible selections open- or short-circuited pi- T-network topologies. For demonstration, four numerical examples with difierent parameters are presented. Furthermore, two microstrip based on open-circuited topologies were fabricated measured. measured results show good performance at dual 1.8/3.45GHz bands. fractional bandwidths deflned by ∞uctuation level difierence less than §0:5dB §5 up to 17% 18%, 18% 2% topologies, respectively.