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Design of compact microstrip lowpass filter with ultra-wide stopband using modified T-shaped resonator

Published online by Cambridge University Press:  09 September 2014

Behnam Afzali ,
Mohammad Mehdi Karkhanehchi  and
Gholamreza Karimi
Behnam Afzali
Affiliation:
Electrical Engineering Department, Islamic Azad University, Science and Research Branch, Kermanshah, Iran
Mohammad Mehdi Karkhanehchi
Affiliation:
Electrical Engineering Department, Engineering Faculty, Razi University, Kermanshah, Iran. Phone: + 98 833 4274536
Gholamreza Karimi*
Affiliation:
Electrical Engineering Department, Engineering Faculty, Razi University, Kermanshah, Iran. Phone: + 98 833 4274536
*
Corresponding author: Gh. Karimi Email: ghkarimi@razi.ac.ir
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Abstract

A new microstrip lowpass filter with compact size and ultra-wide stopband using T-shaped resonator is proposed. To make smaller the circuit size of the filter, cursive transmission line is also suggested. Moreover, exact equation of most important transmission zero is calculated based on LC equivalent circuit and transformation function. A demonstration filter with 3 dB cut-off frequency at 1.02 has been designed, fabricated, and measured. Results show that a relative stopband band width of 166.3% (referred to suppression degree of 20 dB) is achieved while obtaining high figure of merit of 46 274.

Keywords

Lowpass filterTransmission zeroLC equivalent circuit
Type
Research Paper
Information
International Journal of Microwave and Wireless Technologies , Volume 7 , Issue 6 , December 2015 , pp. 699 - 703
Copyright
Copyright © Cambridge University Press and the European Microwave Association 2014 

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References

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