Analysis of novel approach to design of ultra-wide stopband microstrip low-pass filter using modified U-shaped resonator

Gholamreza Karimi*, Ali Lalbakhsh, Khatereh Dehghani, Hesam Siahkamari

*Corresponding author for this work

Research output: Contribution to journalArticle

7 Citations (Scopus)


A novel microstrip low-pass filter is presented to achieve an ultra-wide stopband with 11 harmonic suppression and very sharp skirt characteristics. The filter is composed of a modified U-shaped resonator (which creates two fully adjustable transmission zeroes), a T-shaped resonator (which determines a cut-off frequency), and four radial stubs (which provide a wider stopband). The operating mechanism of the filter is investigated based on a proposed equivalent-circuit model, and the role of each section of the proposed filter in creating null points is theoretically discussed in detail. The presented filter with 3 dB cut-off frequency (fc = 2.35 GHz) has been fabricated and measured. Results show that a relative stopband bandwidth of 164% (referred to as a 22 dB suppression) is obtained while achieving a high figure-of-merit of 15,221.

Original languageEnglish
Pages (from-to)945-950
Number of pages6
JournalETRI Journal
Issue number5
Publication statusPublished - 1 Oct 2015
Externally publishedYes



  • Microstrip low-pass filter
  • U-shaped resonator
  • Ultra-wide stopband

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