Аналитическое решение задачи синтеза трехзвенного ступенчатого чебышевского СВЧ-фильтра

The problem of synthesis of the three–link stepped Chebyshev's microwave filter is reduced to two independent fourth degree equations, including a single link wave impedance as unknown. The solution of Descartes – Euler is applied to these equations. It is proved, that in case of wave impedances of extreme links are equal, the problem of the filter synthesis has two solutions. Identical phase–frequency responses correspond to these solutions. It is proved, that for every one of links a product of the wave impedances, relating to these solutions, is equal to a square of the wave impedance of transmission line, including filter.

Coupling Matrix Extraction of Microwave Filters by Using One-Dimensional Convolutional Autoencoders

The tuning of microwave filter is important and complex. Extracting coupling matrix from given S-parameters is a core task for filter tuning. In this article, one-dimensional convolutional autoencoders (1D-CAEs) are proposed to extract coupling matrix from S-parameters of narrow-band cavity filter and apply this method to the computer-aided tuning process. The training of 1D-CAE model consists of two steps. First, in the encoding part, one-dimensional convolutional neural network (1D-CNN) with several convolution layers and pooling layers is used to extract the coupling matrix from the S-parameters during the microwave filters’ tuning procedure. Second, in the decoding part, several full connection layers are employed to reconstruct the S-parameters to ensure the accuracy of extraction. The S-parameters obtained by measurement or simulation exist with phase shift, so the influence of phase shift must be removed. The efficiency of the presented method in this article is validated by a sixth-order cross-coupled filter simulation model tuning example.