A ${Z}$-Transform Method for Synthesis of Unequal-Length Multisection Transmission Lines for Multiband Applications

Joonsuk Kim, Yongshik Lee

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

A method based on the $Z$-transform is demonstrated to cascade transmission line sections of unequal lengths and achieve multiband and/or wideband properties. Unlike previous methods based on the $Z$-transform, the proposed method associates the $z^{-1}$ term with the infinitesimal length of the unit segment. Consequently, any electrical length can be expressed in the $z^{-1}$ form. Therefore, while the previous methods are restricted to cascading lines of a commensurate length only, the proposed method can be applied to those of incommensurate lengths. Furthermore, the $z$-polynomials for triple or more bands can be constructed by multiplying a combination of single- A nd dual-band polynomials, which remarkably simplifies the entire procedure to develop multiband and/or wideband circuits with virtually no limitation in terms of the number and/or combination of frequencies. The validity and practicality of the proposed method is verified with experimental results for various impedance transformers for real loads and Wilkinson power dividers; the results show the independence in the number and combination of operating frequencies as well as a dual-band operation with a center frequency ratio as large as 7.75.

Original languageEnglish
Article number7886282
Pages (from-to)3200-3210
Number of pages11
JournalIEEE Transactions on Microwave Theory and Techniques
Volume65
Issue number9
DOIs
Publication statusPublished - 2017 Sep 1

Fingerprint

Z transforms
transmission lines
Electric lines
Polynomials
polynomials
synthesis
broadband
dividers
transformers
Networks (circuits)
cascades
impedance

All Science Journal Classification (ASJC) codes

  • Radiation
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

Cite this

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abstract = "A method based on the $Z$-transform is demonstrated to cascade transmission line sections of unequal lengths and achieve multiband and/or wideband properties. Unlike previous methods based on the $Z$-transform, the proposed method associates the $z^{-1}$ term with the infinitesimal length of the unit segment. Consequently, any electrical length can be expressed in the $z^{-1}$ form. Therefore, while the previous methods are restricted to cascading lines of a commensurate length only, the proposed method can be applied to those of incommensurate lengths. Furthermore, the $z$-polynomials for triple or more bands can be constructed by multiplying a combination of single- A nd dual-band polynomials, which remarkably simplifies the entire procedure to develop multiband and/or wideband circuits with virtually no limitation in terms of the number and/or combination of frequencies. The validity and practicality of the proposed method is verified with experimental results for various impedance transformers for real loads and Wilkinson power dividers; the results show the independence in the number and combination of operating frequencies as well as a dual-band operation with a center frequency ratio as large as 7.75.",
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A ${Z}$-Transform Method for Synthesis of Unequal-Length Multisection Transmission Lines for Multiband Applications. / Kim, Joonsuk; Lee, Yongshik.

In: IEEE Transactions on Microwave Theory and Techniques, Vol. 65, No. 9, 7886282, 01.09.2017, p. 3200-3210.

Research output: Contribution to journalArticle

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