This paper investigates the impedance boundary of impedance matching networks analytically, graphically representing the resultant impedance matching domains. A set of explicit equations is derived to allow the rapid development of the impedance boundary of such networks. The equations are analyzed thoroughly, such that the impact each component has upon the resultant domain may be obtained. These equations are then developed further to provide a design procedure enabling a matching network to be designed to achieve impedance matching in a specific impedance domain given the source impedance and operating frequency.