ECE 6130 Power Dividers IIText Section 7.1 continued and 7.2How do you design a power divider? See for examples Chapter 7, Problems 2,4,5Take: Couplers, handout from other text on couplersExample: Problem 7.3Review Minickt sheets on couplers (parameter definitions)4-Port Directional Coupler Parameter Definitions:Coupling C = 10 log (P1/ P3)Directivity D = 10 log (P3/P4)Isolation I = 10 log(P1/P4)Use as a 3-port device:VSWR = Vmax / Vmin on port 1Isolation: Coupling (on either P2 or P3) = 10 log (P1/P2) or (P1/P3)(This is a positive # ... 3dB coupling means that P2 = P1/2)T-Junction Power Divider:jB is mismatch due to reflections at junction. It is usually small (designed to be so) or is negated by adding a lumped element at junction.Yin = jB + 1/Z1 + 1/Z2For matched network: Zin = 1/Yin = ZoFor jB small: 1/Z1 + 1/z2 = 1/ZoDesign Power Divider:Desire output powers to have a 3:1 ratio. Pin = (0.5) Vo2 / ZoP2 = Pin / 4 = (0.5) Vo2 / Z2P3 = 3*Pin / 4= (0.5) Vo2 / Z3Z2 = 4 Zo = 200 ohms for Zo = 50 ohmsZ3 = 4 Zo/3 = 67 ohmsInput impedance Zin = Z2 || Z3 = 50 ohms (This will be matched by definition, because we didn’t allow power to go anywhere else.)Ports 2 and 3 are not matched. There will be reflections there, that can be removed by adding matching network (single stub?).Advantages: LosslessDisadvantages: Mismatched at output ports AND no isolation between output ports. (Generally it is desirable for output ports to be uncoupled, in case waves are reflected at one port, they won’t show up at the other port.)RESISTIVE DIVIDER:All three ports can be matched using a resistive power divider. But, in practice, this is notvery useful, because so much power is lost, and so much heat is