• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.5
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• pp.326-332
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• 1999

In this paper, we designed and fabricated High-Tc Superconducting (HTS) microstrip bandpass filters using Stepped Impedance Resonators(SIR) and studied on their characteristics. The $high-T_c$ superconducting $Y_1Ba_2Cu_3O_{7-x}$ epitaxial films were deposited by Pulse Laser Deposition (PLD) system on MgO. The fabricated filters were designed so as to operate in Ku band with central frequency 17.25 GHz, bandwidth 2.896% and ripple 0.01 dB. These filters were composed of parallel coupled microstrip SIR of which impedance ratio (K) are 0.5, 1.5. In the measured response, HTS filters had showed insertion loss below -0.5 dB. For comparison with normal conducting filter, we fabricated the Au counterpart that consists of the resonators as K=1.5 in the same dimension and measured performance of the Au filter. In comparison, HTS filter designed optimally got superior response to gold conterpart.

• Journal of Advanced Navigation Technology
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• v.23 no.1
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• pp.69-76
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• 2019

In this paper, a design method for an enhanced-sensitivity microwave sensor based on microstrip defected ground structure was studied for the permittivity measurement of planar dielectric substrates. The proposed sensor was designed by modifying the ridge structure of an H-shaped aperture into the shape of a capacitor symbol. The sensitivity of the proposed sensor was compared with that of a conventional sensor based on a double-ring complementary split ring resonator(DR-CSRR). Two sensors were designed and fabricated on a 0.76-mm-thick RF-35 substrate so that the transmission coefficient would resonate at 1.5 GHz in the absence of the substrate under test. Five types of taconic substrates with a relative permittivity ranging from 2.17 to 10.2 were selected asthe substrate under test. Experiment results show that the sensitivity of the proposed sensor, which is measured by the shift in the resonant frequency of the transmission coefficient, is 1.31 to 1.62 times higher than that of the conventional DR-CSRR-based sensor.

• Journal of Advanced Navigation Technology
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• v.23 no.5
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• pp.415-423
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• 2019

In this paper, a design method for a high-sensitivity microstrip patch sensor antenna (MPSA) loaded with a bent-slot was studied for the permittivity measurement. The bent-slot similar to a single-ring complementary split ring resonator was added along a radiating edge of the patch in order to enhance the sensitivity to the permittivity. The sensitivity of the proposed MPSA was compared with that of a conventional rectangular MPSA and a thin rectangular-slotted MPSA. Three MPSAs were designed and fabricated on a 0.76-mm-thick RF-35 substrate so that the input reflection coefficient would resonate at 2.5 GHz in the absence of the superstrate under test. When five different Taconic substrates with a relative permittivity ranging from 2.17 to 10.2 were used as the superstrate under test, experiment results show that the sensitivity of the proposed MPSA, which is measured by the shift in the resonant frequency of the input reflection coefficient, is 4.1 to 6.1 times higher than that of the conventional MPSA.

• Journal of information and communication convergence engineering
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• v.8 no.5
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• pp.484-488
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• 2010

In this paper, we present a novel tunable microstrip bandpass filter based on split ring resonators (SRRs). The varactors are reverse-biased semiconductor diode, and are connected between the concentric rings of the SRR. An individual varactor loaded SRR based bandpass tunable filter module is analyzed. Then a second order tunable filter with 7% fractional bandwidth and a tuning range from 2.75 to 2.86 GHz is assembled from basic filter modules. The simulator HFSS (V10) is used to design the tunable filter and to simulate. The results show good characteristics is created.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.697-700
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• 1999

This Paper presents the design, fabrication, analysis of the measured date of a voltage controlled oscillator(VCO) for the application of Personal Communication Systems. Main VCO circuit consists of self biased emitter resonating circuit with microstrip line resonator on FR4 epoxy substrate. A varactor diode is used for 90MHz frequency tuning with center frequency of 1635MHz Phase noise of -114.67㏈C/Hz at 100KHz off set has been achieved with 3.3 V supply. The size of the fabricated VCO circuit is 1.25 cm$\times$ 1.25 cm.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.361-365
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• 2003

In this paper, we proposed the effective serial connection methodology of PBG resonator with defect mode. We use the big difference of impedance ratio in connection region, for example dual PBG, for serial connection. This method reduces the PBG cells and is able to control the pole of bandpass filters. This result in flexibility in design of bandpass filter. Our PBG bandpass filter is modeled by using the ideal transmission line model. This model is very easy, fast, and effective for PBG structure.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.343-346
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• 2003

A new structure to design low pass filters (LPFs) is presented rho proposed structure has the etched shape of Quad-Spiral DGS(Defected Ground Structure) on microstrip transmission lines. By extracting the equivalent circuit elements of unit Quad-Spiral DGS, LPFs are designed easily. The equivalent circuit of Quad-Spiral DGS consists of a step impedance resonator and lumped elements. The proposed LPF provided steep rejection characteristics with 5-poles. Experimental results show excellent agreements with circuit simulation results in wide band and the validity of our circuit modeling for LPF design. The result shows another possibility of Quad Spiral DGS for microwave devices.

• 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.

• Journal of Electrical Engineering and Technology
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• v.8 no.2
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• pp.371-375
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• 2013

The design of a new compact UWB bandpass filter is proposed, which has cascaded center-tapped microstrip composite right/left-handed transmission-line zeroth-order resonators (CRLH-TL ZORs). In an attempt to reduce the size, instead of the conventional half-wavelength resonators or periodic and multiple CRLH-TL cells, only one cell ZOR geometry is adopted as each resonator in the filter. Additionally, two center-tapped ZORs are coupled to increase the slope of the skirt. Besides, stepped impedance matching parts are placed in the paths to the input and output ports to enhance passband and stopband performances. The proposed filter is shown to have the overall size of $0.69{\lambda}_g{\times}0.70{\lambda}_g$, the insertion loss much less than 1 dB, and an acceptable return loss performance in the predicted and measured results.

• ETRI Journal
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• v.29 no.5
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• pp.614-618
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• 2007

A miniaturized bandstop filter (BSF) is introduced in this paper. The filter consists of one meander spurline and a pair of capacitively loaded stubs. The meander spurline with low resonant frequency and improved slow-wave factor exhibits excellent resonant bandgap characteristics which can be modeled by a longitudinally coupled resonator. The design of the proposed microstrip BSF is presented, and its performance is measured. Measurements show that there is a stopband from 2.3 to 5.6 GHz with $S_{21}$ less than -20 dB. The total length of this BSF equals 23 mm.