Fig. 1 The block diagram of the transmission line impedance transformer(TLT); (a) λ/4-microstrip line TLT, and (b) λ/4-coaxial line TLT
Fig. 2 The wideband TLT using two coaxial lines
Fig. 3 The circuit block diagram for the operation characteristic analysis of λ/4-microstrip line TLT; (a) S11 measurement, and (b) S21 measurement
Fig. 4 4:1 coaxial cable TLT using 12.5-Ω microstrip line length of 27.29mm(45° at 900MHz); (a) Fabrication photograph, (b) One-port characteristic(S11), and (c) Two-port characteristic (S11 & S21)
Fig. 5 Minimum S11 measurement according to the length of 12.5Ω microstrip line; (a) Measurement block diagram, and (b) Measurement result
Fig. 6 Fabrication photograph of wideband 4:1 coaxial line TLT
Fig. 7 Operation characteristic(S11&S21) of the wideband 4:1 coaxial line TLT according to the length of 12.5Ω microstrip line; (a) 27.29mm(45° at 900MHz), (b) 49.14mm(45° at 500MHz), and (c) 122.86mm(45° at 200MHz)
Table. 1 S21 characteristic due to the length(α2) of the middle microstrip line
Table. 2 Minimum S11 value according to the length of 12.5Ω microstrip line in wideband 4:1 coaxial line TLT
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