This chapter first introduces kQ formulas of simple inductive and capacitive couplers by way of their equivalent circuits. We then derive the optimum load impedance formula that brings the coupler into play at its best efficiency. The formulas are finally generalized to a unified theory that can apply to any kind of coupler represented by a two-port reciprocal black box.

Chapter Contents:

• 5.1 Introduction
• 5.2 Inductive coupler
• 5.2.1 Equivalent circuit
• 5.2.2 Coupling coefficient
• 5.2.3 Q factor
• 5.2.4 Coupling Q factor
• 5.2.5 Optimum impedance
• 5.2.6 Maximum efficiency
• 5.3 Capacitive coupler
• 5.3.1 Equivalent circuit
• 5.3.2 Coupling coefficient
• 5.3.3 Q factor
• 5.3.4 Coupling Q factor
• 5.3.5 Optimum admittance
• 5.3.6 Maximum efficiency
• 5.4 Generalized formulas
• 5.4.1 Two-port black box
• 5.4.2 Impedance matrix
• 5.4.3 Generalized kQ
• 5.4.4 Optimum load and input impedance
• 5.4.5 Maximum efficiency
• 5.5 Conclusion
• Appendix A
• A.1 Measurement of kQin practice
• Acknowledgments
• References

Inspec keywords: passive networks; equivalent circuits; waveguide couplers

Other keywords: capacitive couplers; inductive couplers; equivalent circuits; two-port reciprocal black box; wireless couplers; kQ formulas; circuit theory; optimum load impedance formula

Subjects: Passive filters and other passive networks; Waveguide and microwave transmission line components