高阶S21拟合策略在耦合矩阵提取方法中的运用

doi:10.19665/j.issn1001-2400.20240204

Abstract

Abstract:

Fitting the measured or simulated sampled data by a rational function model is an important step in a filter coupling-matrix-extraction method.A high-order transmission coefficient(S₂₁) fitting strategy is proposed to address the problem of the deviation between the fitted and sampled data near the transmission zeros with small amplitudes.This strategy achieves a high fitting accuracy by fitting the sampled transmission coefficient with a rational function with a numerator polynomial of Nth-order(N being the order of filter) to accurately locate the transmission zeros.Then,the numerator polynomial of the transmission coefficient is reconstructed by selecting the N_z(N_z being the number of transmission zeros of the real filter) desired transmission zeros among the N fitted transmission zeros to guarantee that the number of transmission zeros of the extracted coupling matrix is the same as that of the real filter.For verification,a ninth-order coaxial filter with three transmission zeros is used as an example to validate the conventional Cauchy method,the Cauchy method that applies the higher-order transmission coefficient fitting strategy,and the model-based vector fitting method(MVF).The results show that this strategy can improve the fitting accuracy near the transmission zeros.Since the robustness of the Cauchy method is not high enough,a coupling-matrix-extraction method by identifying the zeros of S-parameters using vector fitting is proposed in this paper by consisting the operation steps of the Cauchy method and MVF,this method can fit the zero of S-parameters more accurately than MVF and has a less influence by noise than the Cauchy method.

Key words: microwave filters, equivalent circuits, coupling-matrix-extraction, Cauchy method, vector fitting

CLC Number:

TN713+.5

XIE Hanyu, WU Bian, YANG Yimin, ZHAO Yutong, CHENG Yingxin, CHEN Jianzhong, SU Tao. Application of the high-order S₂₁ fitting strategy in coupling-matrix-extraction methods[J].Journal of Xidian University, 2024, 51(4): 15-28.

Figures/Tables 10

References 16

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耦合系数	状态a	状态b	状态c	状态d	目标	耦合系数	状态a	状态b	状态c	状态d	目标
M₁₁	0.145 2	-0.055 9	0.003 7	0.010 1	0.012 2	M₁₂	0.707 1	0.788 3	0.757 8	0.756 2	0.756 3
M₂₂	-0.042 5	-0.736 7	-0.538 7	-0.518 6	-0.521 2	M₁₃	0.373 1	0.376 6	0.382 2	0.382 1	0.386 5
M₃₃	0.361 5	-0.015 0	0.087 0	0.088 5	0.086 2	M₂₃	0.566 1	0.490 7	0.501 2	0.501 4	0.505 0
M₄₄	-0.133 9	-0.132 0	-0.005 6	0.040 9	0.042 8	M₃₄	0.422 2	0.547 9	0.554 4	0.553 3	0.554 5
M₅₅	-0.483 1	-0.452 6	-0.286 6	-0.263 2	-0.263 5	M₄₅	0.600 3	0.500 7	0.502 0	0.524 5	0.520 1
M₆₆	-0.218 0	-0.038 4	-0.022 8	0.031 5	0.040 8	M₄₆	0.186 2	0.141 8	0.143 6	0.148 1	0.150 4
M₇₇	0.320 9	0.014 6	0.083 3	0.082 0	0.080 0	M₅₆	0.509 7	0.508 4	0.509 2	0.516 3	0.520 3
M₈₈	-0.543 3	-0.327 3	-0.402 3	-0.472 0	-0.464 4	M₆₇	0.539 8	0.553 9	0.554 5	0.553 5	0.554 3
M₉₉	0.089 7	-0.069 7	0.002 5	-0.002 1	0.012 2	M₇₈	0.492 3	0.558 0	0.555 2	0.523 4	0.524 7
M_S₁	1.016 4	1.026 3	1.023 5	1.022 7	1.026 5	M₇₉	0.247 4	0.267 8	0.276 5	0.343 2	0.344 3
M₉_L	1.021 6	1.027 3	1.023 7	1.022 0	1.026 5	M₈₉	0.775 5	0.816 3	0.809 9	0.782 0	0.777 2

Application of the high-order S₂₁ fitting strategy in coupling-matrix-extraction methods

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[2]	ZHANG Yongliang;SU Tao;WU Bian;LIANG Changhong. Method for triplexer rational model extraction [J]. J4, 2013, 40(6): 92-95.
[3]	ZHANG Yongliang;SU Tao;WU Bian;LIANG Changhong. Multiplexer rational models extraction based on the improved Cauchy method [J]. J4, 2013, 40(3): 201-204.
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[5]	HAN Ying-bin1;ZHAO Yong-jiu1;LU Hong-min2. Coupling matrix method for diagnosis and tuning of microwave filters [J]. J4, 2008, 35(4): 703-706.

Application of the high-order S21 fitting strategy in coupling-matrix-extraction methods

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Application of the high-order S₂₁ fitting strategy in coupling-matrix-extraction methods