Dissipative canonical nonuniform transmission lines as basic components of power dividers with distributed isolation impedance

Abstract

It is well known that power dividers (PD) on nonuniform transmission lines (NUTL) with distributed isolation theoretically have no upper boundary of the operating frequency range in a single-wave approximation. This allows one to solve the problem of creating superwide-band microwave power divider in a natural way. For computation of such devices it is necessary to know the matrix parameter of the NUTL sections which, as it is known, can be found by solving linear differential equations of the second order with variable coefficients. Such solutions have been found for some types of NUTLs. However, they may not be applied to the computation of a power divider with distributed isolation since they have been obtained for loss-less lines. Therefore another computation method has gained acceptance: nonuniform lines are being replaced by cascade connection of stepped uniform transmission lines (UTL), and the distributed isolation impedance is replaced by the lumped one within each step. This method, being universal, has a number of drawbacks. A new type of NUTL namely the canonical nonuniform transmission line (CNUTL) has been suggested. The impedance function of CNUTL depends on two real parameters, and for their reasonably definite numerical values it assumes specific form which correspond to exponential, parabolic, hyperbolic, cosine-, sine-square, and other lines widely used in microwave engineering. This work is aimed at the generalization of the theory of the canonical nonuniform transmission lines for the case of dissipative lines and the study of their potential as structural elements of power dividers with distributed isolation impedance.