Research of Long Lines with Constant and Variable Parameters using a Symbolic Method

The paper presents the results of modelling a long line with discrete elements with dimensions much smaller than the wavelength. The system UDF MAOPCs (user-defined functions for multivariate analysis and optimization of parametric circuits), based on the frequency symbolic method of analysis of both circuits with constant and circuits with time-varying parameters (linear periodically-time-varying circuits), is used for its research There is provided a comparison of results obtained using the symbolic analysis method with the results obtained by the numerical and classical methods of the distributed parameters circuits analysis. There is provided a number of computer experiments that prove the effectiveness of the system UDF MAOPCs application to the analysis and research of long lines both with constant parameters, and lines with variable parameters. The considered models are useful when designing the radio engineering devices modelled with linear periodically-time-varying circuits, and, in particular, devices of noise-resistant secret radio engineering systems of special purpose.