• Journal of electromagnetic engineering and science
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• v.8 no.4
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• pp.144-147
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• 2008

This paper proposes a tunable combline bandpass filter with high selectivity, constant bandwidth, and good stopband performances. A filter with these characteristics is obtained by applying cross-coupling to the conventional combline bandpass filter using stepped-impedance resonators(SIRs). For high selectivity and constant bandwidth, cross-coupling is utilized and the SIR configuration is used for enhanced stopband performances. The proposed combline tunable bandpass filter with 5% of fractional bandwidth at 1.6 GHz was fabricated and tested. The measured results showed 11.6% tunability with constant bandwidth, high selectivity and enhanced stopband characteristics.

• JSTS:Journal of Semiconductor Technology and Science
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• v.11 no.1
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• pp.65-72
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• 2011

In this paper, the T-shape stepped impedance resonators are adopted for the design of microstrip bandpass filters for wide harmonics suppression. The proposed filters are operated at the center frequency of 2.44 GHz and 5.20 GHz, respectively. These bandpass filters have been also applied for a high performance diplexer. The insertion losses at the center frequencies of 2.44 and 5.20 GHz are 1.23 and 1.18, respectively. The applicable return losses for both frequency bands and a wide stopband better than 17 dB up to 20 GHz have been obtained.

• Journal of electromagnetic engineering and science
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• v.15 no.1
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• pp.26-30
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• 2015

In this paper, a simple equivalent circuit model for a defected ground structure (DGS) microstrip line with stepped impedance slot-lines in the ground plane is presented. In addition, an analytic expression for the resonance frequency of the proposed structure is derived. In equivalent circuit modeling, the capacitance and the inductance of the resonance circuit are evaluated from the dimensions of the etched pattern in the ground plane. The resonance frequencies calculated from the proposed method are compared with those obtained with an electromagnetic (EM) simulation.

• Journal of electromagnetic engineering and science
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• v.18 no.2
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• pp.73-77
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• 2018

This paper proposes a dual-band bandpass filter using stepped-impedance resonators (SIRs) with parallel coupled structures. The proposed filter adopts U-shaped SIRs with parallel coupled lines (PCLs) that have interdigital and comb-line shorted ends. The central PCLs build an upper passband and a transmission zero, and the two U-shaped SIRs build a lower passband. Four resonators and coupling structures are theoretically analyzed to derive its scattering parameters. A novel dual-band bandpass filter is designed and fabricated using the induced scattering characteristics. The measured results show that the fabricated dual-band bandpass filter has an insertion loss of less than 1.02 dB in the lower band of 2.45 GHz and of 3.01 dB in the upper band of 3.42 GHz, and a band-to-band isolation of more than 40 dB, from 3.14 to 3.2 GHz.

• Journal of electromagnetic engineering and science
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• v.11 no.2
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• pp.83-90
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• 2011

In this paper, we present the design method for a low-pass type inverter, which can effectively suppress the spurious response associated with band-pass filters. The inverter has a length of ${\lambda}/4$ and employs not only a stepped-impedance configuration but also asymmetrical and bending structures in order to improve frequency selectivity and compactness. The inverter is applied as an impedance/admittance inverter to the ultra-wideband (UWB) band-pass filter. The UWB band-pass filter configuration is based on a stub band-pass filter consisting of quarter-wavelength impedance inverters and shunt short-circuited stubs ${\lambda}/4$ in length. The asymmetrical stepped-impedance low-pass type inverter improves not only the spurious responses, but also the return loss characteristics associated with a UWB band-pass filter, while a compact size is maintained. The UWB band-pass filter using the proposed inverters is fabricated and tested. The measured results show excellent attenuation characteristics at out-band frequencies, which exceed 18 dB up to 39 GHz. The insertion loss within the pass-band (from 3.1 to 10.6 GHz) is below 1.7 dB, the return loss is below 10 dB, and the group delay is below 1 ns.

• ETRI Journal
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• v.35 no.2
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• pp.344-347
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• 2013

This letter presents a compact dual-mode tri-band bandpass filter by using a short-circuited stub-loaded stepped-impedance resonator (SIR) and a short-circuited stub-loaded uniform impedance resonator. Also, a hairpin SIR geometry is introduced to miniature the size of this filter while maintaining excellent performance. The use of a short-circuited stub at the central point of the hairpin SIR can generate two resonant modes in two passbands. Its equivalent circuit structure is analyzed by using the even-odd mode theory. For demonstration purposes, a tri-band filter for the applications of the Global Positioning System at 1.57 GHz, Worldwide Interoperability for Microwave Access at 3.5 GHz, and wireless local area networks at 5.2 GHz is designed, fabricated, and measured.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.2
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• pp.245-251
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• 2011

In this paper, dual-band bandpass filter by using Pseudo-Interdigital Stepped-Impedance Resonator(PI-SIR) and Open-Loop Ring Resonator(OLRR) is proposed. The first passband and second passband are formed by PI-SIR and the second passband is reinforced by an OLRR. In a PI-SIR the first band and second band are easily and exactly adjusted by characteristic impedance ratio and electrical length ratio. The proposed design method may be confirmed to be useful from fabricated and measured results for dual-band bandpass filter operated at 2.45 GHz and 5.8 GHz.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.07a
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• pp.318-318
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• 2004

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.2 no.4
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• pp.10-16
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• 1991

A microstrip bandpass filter using stepped impedance resonators and tapped input / output is realized with Teflon substrate, whose center frequency is 3.5 GHz and fractional bandwidth is 20%. In order to realize a wider bandwidth of 30%, the Crystal's design method and the input / output tapping scheme are used. Another microstrip filter designed as mentioned above is realized with Epsilam-10 substrate. This case shows good agreement between the theoretical responses and the measured ones.

• Journal of Advanced Navigation Technology
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• v.27 no.1
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• pp.57-62
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• 2023

This paper proposes a tri-band bandpass filter using dual-mode stepped-impedance resonators (SIRs) with parallel coupled structures. The proposed filter adopts U-shaped SIRs with open stubs and parallel coupled lines (PCLs) that have inter-digital and comb-line shorted ends. Two U-shaped SIRs with open stubs build the first and third passband, and the central PCL resonators build the second passband. Five resonators and coupling structures are theoretically analyzed to derive the scattering parameters of the proposed filter. A novel tri-band bandpass filter is designed and fabricated using the induced scattering parameters. The measured result of the fabricated tri-band bandpass filter shows a good agreement with the simulated one.