AN EQUIVALENT CIRCUIT FOR MICROWAVE DISCONTINUITIES

An equivalent circuit for discontinuities exciting evanescent accessible modes is proposed. The key feature of this equivalent circuit is its capability for simplification if a port relative to an accessible evanescent mode is matched, or connected to a very long line. Circuit drawing is simple and fast and is based on a regular polygon with as many susceptances as the sides and the diagonals. Each side is connected with a line of electrical length  to the terminal ports and, if the port refers to an evanescent accessible mode, a series reactance is added. This reactance is the key to the evanescent part of the circuit because it is able to cancel the effect of the evanescent mode if the port is matched or connected to a very long evanescent line, reducing the complexity of the circuit by one degree.