Journal of Xidian University ›› 2019, Vol. 46 ›› Issue (3): 154-159.doi: 10.19665/j.issn1001-2400.2019.03.023

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Matrix optimization synthesis method for the cross-coupled filter with frequency dependent couplings

LI Gang   

  1. School of Physics and Electronic Engineering, Hubei University of Arts and Science, Xiangyang 441053, China
  • Received:2018-12-20 Online:2019-06-20 Published:2019-06-19

Abstract:

The traditional coupling coefficients in the cross-coupled filter model do not accurately characterize the frequency characteristics of the coupled structure under the broadband condition. To solve this problem, a matrix optimization synthesis method for the N+2 cross-coupled filter with frequency dependent coupling coefficients is proposed. First, the N+2 frequency dependent coupling matrix of a given topology is transformed into a frequency independent coupling matrix by matrix scaling and similarity transformation. Then, the objective function is constructed by approaching the eigenvalues of the N+2 canonical coupling matrix. Finally, the N+2 frequency dependent coupling matrix with a specified topology can be obtained by the gradient optimization algorithm. Numerical synthetical results of different topologies prove that the proposed method can efficiently solve the synthesis problem of filters with complex frequency dependent couplings.

Key words: coupling matrix, frequency dependent coupling, equivalent circuits, synthetical techniques, microwave filter

CLC Number: 

  • TN713.5

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