• 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.33 no.6
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• pp.981-984
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• 2011

A novel lowpass filter with a very sharp transition band and wide stopband is proposed. The proposed filter is based on T-shaped patches which are etched in symmetrical structures and folded open stub. To obtain a wide stopband, we have used stub loaded semi-circle stepped-impedance structures. By designing the resonator with high inductance and capacitance, a very sharp transition band is achieved. The proposed filter has a 3-dB cutoff frequency at 2.37 GHz and a 40-dB rejection at 2.44 GHz. The stopband with an attenuation level better than -13.2 dB is up from 2.4 GHz to 16 GHz, and consequently we have reached the high and wide rejection in stopband with compact size. Good agreements between the simulated and the measured results are presented.

• 한국ITS학회:학술대회논문집
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• 2004.11a
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• pp.224-227
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• 2004

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.10
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• pp.1169-1174
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• 2014

In this paper, for improving the performance of selecting and the sensitivity of the L-Band microwave radiometer for remote sensing of soil-moisture, the harmonic-suppressed hairpin bandpass filter is described. As the harmonic frequencies of the SIR can be controlled by the ratio of the impedance and electrical length, SIRs are used in the hairpin BPF for suppressing harmonics. Manufactured harmonic-suppressed hairpin BPF has the SIRs of three types and its harmonic is suppressed under 35 [dB] until 5 times of the center frequency of 1390 [MHz].

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.11
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• pp.84-90
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• 2010

In this paper, the reduced size of broad bandpass filter with parallel coupled line structure is presented. This proposed filter can control bandwidth of narrow to broadband by adjusting the coupling coefficient. The conventional filter is operated with a narrow band. If a higher bandwidth is desired than the conventional narrow bandwidth, it is hard to realize due to the coupling coefficient between feeding line and resonator. In this paper, to overcome this limitation, a proposed bandpass filter is designed with reduced size due to SIR(Stepped Impedance Resonator) and multi-grade type structures than conventional one, and it has characteristics of adjusting bandwidth freely as per quantity of coupling coefficient. The proposed bandpass filter that, experimental results of insertion and return losses are 0.42 dB and 20.9 dB with bandwidth of 60 % at the center frequency of 5.8 GHz, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.4A
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• pp.407-413
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• 2011

In this paper, the reduced size of broad bandpass filter with parallel coupled line structure is presented. This proposed filter can control bandwidth of narrow to broadband by adjusting the coupling coefficient. The conventional filter is operated with a narrow band. If a higher bandwidth is desired than the conventional narrow bandwidth, it is hard to realize due to the coupling coefficient between feeding line and resonator. In this paper, to overcome this limitation, a proposed bandpass filter is designed with reduced size due to SIR (Stepped Impedance Resonator), U-shaped open stub with hair-pin and vertical-type structure than conventional one, and it has characteristics of adjusting bandwidth freely as per quantity of coupling coefficient. The proposed bandpass filter that, experimental results of insertion and return losses are 0.42 dB and 24.5 dB with bandwidth of 60 % at the center frequency of 5.8 GHz, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.9
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• pp.956-963
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• 2002

A linearly polarized folded type and H-shape slit folded type microstrip patch antenna at GPS(center frequency:1.575 GHz) were designed and fabricated by folding a conventional single $\lambda_{g}/2(\lambda_{g}:wavelength)$ rectangular patch a half along the length direction at the center of patch and inserting ground plane in the middle. As a result, two types of omnidirectional radiation patterns for E-plane (for zx-plane) in the direction of the length of patch and H-plane (for xy-plane) have been acquired. The experimental results show that the average gains of folded type and slit folded type for omnidirectional E-plane and H-plane are -1.5 dBd (-2.4 dBd) and -3.27 dBd(-2.5 dBd). Slit folded type microstrip patch antenna was more miniaturized than folded type microstrip patch antenna by 27.5 %. In case of slit folded type antenna, average gains of omnidirectional radiation pattern for E & H-plane are almost same.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.12
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• pp.59-64
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• 2009

In this paper, the design of a new bandstop filter with an ultra-wide stopband is proposed using the metamaterial CRLH-TL. Instead of conventional periodic structures and multi-staged CRLH-TLs, extremely small one-cell type is adopted to circumvent the setbacks of conventional filters such as the lengthened ${\lambda}_g/2$-resonator ones or alternating impedance lowpass filter, and relatively slow skirt. Besides, for a very broad stopband, a strong coupling structure including stepped impedances is suggested and the zero-order resonance is made for effective size-reduction. The validity of the proposed design is proven through the fabrication and measurement, showing the overall size less than ${\lambda}_g/10$, the stopband wider than 12 GHz, 0.7 dB of the insertion loss.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.12
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• pp.1447-1453
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• 2010

In this paper, the design and the fabrication of dual-band bandpass filter using two dual-mode resonators is presented. Dual-mode resonator using a short stub is miniaturized by inter-digital capacitor and stepped impedance. Two dual mode resonators are designed to have different resonant frequencies, one for the lower passband and the other for the upper passband. Transmission zero is positioned at low or high rejection bands with a sharp skirt characteristic. Dual-band operation can be achieved using dual feeding structure. For WLAN, the proposed filter at 2.45/5.25 GHz is designed and fabricated. The size of the filter is as compact as 1$10.83\;mm{\times}5.3\;mm$.