Unified Expression of the Conjugate Image Impedances for Two-port Representations

. Conjugate image impedances are used to minimize power reflections in a variety of domains, including amplifier design, microwave engineering, wireless power transfer, antenna design and millimeter wave applications. For a two-port network, they can be described as function of different parameters including impedance, admittance, hybrid, inverse hybrid, chain, scattering and chain scattering parameters. In this work, a general unified structure for the conjugate image impedances is provided, valid for each of the two-port representations. It highlights its close relationship with the Rollett stability factor and provides insight into the structure of conjugate image impedances. choice of the proper S parameters in characterizing devices including transmission lines with complex ref- erence impedances and a general methodology for computing them.