9 - Further topics

Abstract

This chapter provides provide an introduction to signal flow graph analysis. Occasions often arise where a network is extremely cumbersome and difficult to understand, and it is hard to solve the circuit parameters by algebraic means. In such cases, signal flow graph analysis is used to help understanding, and to reduce circuit complexity until it can be handled easily by more conventional algebraic methods. Signal flow analysis is used as a means of writing and solving linear microwave network equations. It is direct and relatively simple; variables are represented by points and the inter-relations between points are represented by directed lines giving a direct picture of signal flow. The easiest way to understand signal flow manipulation is by examples, thus several methods of applying signal flow analysis is discussed. The computer aided design programs discussed in this chapter, namely AppCAD, PUFF and Motorola's Impedance Matching Program (MIMP) are extremely low cost and provide a very good cross-section of theoretical and practical constructional techniques for microwave radio devices and circuits. AppCAD is used extensively for checking the bias and matching circuits. MIMP is used extensively for checking the Smith chart results.