Including Stripline Modes in the Y-Junction Circulators: Revisiting Fundamentals and Key Design Equations

Abstract

Junction circulators are internally matched n-port devices where the input signal to a specific port transfer to the adjacent port and isolated from all other ports. Circulators and isolators are used extensively in many communication systems and defense applications. They are used in splitting the forward and reverse signals in radar applications, which facilitates the signal processing and protects the critical system components such as amplifiers. Most of the current design techniques of circulators presented in the literature have no straightforward procedure and embrace many empirical equations. Such techniques provide approximate and iterative solutions, which increase the time and cost of the development process to achieve the required specifications. In this paper, we present a simple circulators design methodology based on a closed-form solution of the stripline Y-junction including the stripline modes. In addition, we criticize the traditional design methodologies and highlight their limitations and shortcomings. We validate the proposed procedure by two designs for the junction circulators based on the stripline technology. The provided closed-form solution is a revolutionary design methodology as it reduces the lengthy approximate expensive trials to a straightforward and systematic cost-effective technique.