PROJECT TITLE :

Two-section asymmetric coupled-line impedance transforming directional couplers

ABSTRACT:

Two-section impedance transforming directional couplers have been proposed. It's been shown that such asymmetric coupled-line directional couplers will offer equal power split between the coupled and transmission ports also impedance transformation in the same broad frequency range, as classic 2-section coupled-line couplers. The theoretical analysis has been presented and appropriate formulas allowing for calculation the specified per-unit-length parameters of broadband two-section impedance transforming couplers have been derived. Moreover, it's been shown that the impedance transformation ratio of the presented coupler will be increased by the acceptable modification of the 2-section coupled-line directional coupler during a way that the directly fed and coupled-line transformation ratios are different. The proposed modification permits for the planning of broadband impedance remodeling directional couplers with increased transformation ratio over the limit fastened by the coupling coefficient of the tightly coupled section and having at the identical time acceptable impedance match and isolation between the respective ports. The presented theory has been confirmed by the measurements of a 2-section 3 dB impedance transforming directional coupler having bandwidth fu/fl = 3:one and impedance transformation ratio R = 2.