Design of parallel-coupled microstrip filters with suppression of spurious resonances using substrate suspension

Jen Tsai Kuo; Meshon Jiang; Hsien Jen Chang

doi:10.1109/TMTT.2003.821247

Design of parallel-coupled microstrip filters with suppression of spurious resonances using substrate suspension

Jen Tsai Kuo^*, Meshon Jiang, Hsien Jen Chang

^*Corresponding author for this work

National Yang Ming Chiao Tung University

Research output: Contribution to journal › Journal Article › peer-review

109 Scopus citations

Abstract

Substrate suspension is used to suppress the spurious response of microstrip bandpass filters at twice the passband frequency (2f_o). It is known that a proper height of substrate suspension can be used to equalize the even- and odd-mode phase velocities for coupled microstrip lines. In this paper, this property is applied to design the coupled stages of a parallel-coupled line filter so that the spurious response at 2 f_o can be completely suppressed. The individual image impedance for each coupled stage is changed accordingly. Required filter design formulas are derived for a series of coupled stages having different image impedances. Several filters made on a substrate of relative high dielectric constant are designed and fabricated. The measured results show that a rejection level of better than -40 dB to the spurious resonance at 2 f_o can be obtained.

Original language	English
Pages (from-to)	83-89
Number of pages	7
Journal	IEEE Transactions on Microwave Theory and Techniques
Volume	52
Issue number	1 I
DOIs	https://doi.org/10.1109/TMTT.2003.821247
State	Published - 01 2004
Externally published	Yes

Keywords

Image impedance
Parallel-coupled microstrip filter
Spurious response
Suspended substrate

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10.1109/TMTT.2003.821247

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abstract = "Substrate suspension is used to suppress the spurious response of microstrip bandpass filters at twice the passband frequency (2fo). It is known that a proper height of substrate suspension can be used to equalize the even- and odd-mode phase velocities for coupled microstrip lines. In this paper, this property is applied to design the coupled stages of a parallel-coupled line filter so that the spurious response at 2 fo can be completely suppressed. The individual image impedance for each coupled stage is changed accordingly. Required filter design formulas are derived for a series of coupled stages having different image impedances. Several filters made on a substrate of relative high dielectric constant are designed and fabricated. The measured results show that a rejection level of better than -40 dB to the spurious resonance at 2 fo can be obtained.",

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AU - Kuo, Jen Tsai

AU - Jiang, Meshon

AU - Chang, Hsien Jen

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N2 - Substrate suspension is used to suppress the spurious response of microstrip bandpass filters at twice the passband frequency (2fo). It is known that a proper height of substrate suspension can be used to equalize the even- and odd-mode phase velocities for coupled microstrip lines. In this paper, this property is applied to design the coupled stages of a parallel-coupled line filter so that the spurious response at 2 fo can be completely suppressed. The individual image impedance for each coupled stage is changed accordingly. Required filter design formulas are derived for a series of coupled stages having different image impedances. Several filters made on a substrate of relative high dielectric constant are designed and fabricated. The measured results show that a rejection level of better than -40 dB to the spurious resonance at 2 fo can be obtained.

AB - Substrate suspension is used to suppress the spurious response of microstrip bandpass filters at twice the passband frequency (2fo). It is known that a proper height of substrate suspension can be used to equalize the even- and odd-mode phase velocities for coupled microstrip lines. In this paper, this property is applied to design the coupled stages of a parallel-coupled line filter so that the spurious response at 2 fo can be completely suppressed. The individual image impedance for each coupled stage is changed accordingly. Required filter design formulas are derived for a series of coupled stages having different image impedances. Several filters made on a substrate of relative high dielectric constant are designed and fabricated. The measured results show that a rejection level of better than -40 dB to the spurious resonance at 2 fo can be obtained.

KW - Image impedance

KW - Parallel-coupled microstrip filter

KW - Spurious response

KW - Suspended substrate

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M3 - 文章

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JO - IEEE Transactions on Microwave Theory and Techniques

JF - IEEE Transactions on Microwave Theory and Techniques

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Design of parallel-coupled microstrip filters with suppression of spurious resonances using substrate suspension

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Keywords

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