• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.1
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• pp.103-109
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• 2008

In this papaer, a new type of ${\lambda}_g/4$ short stub band pass filter and ${\lambda}_g/2$ open stub band pass filter are purposed. Both are designed using FSCS technique for harmonic suppression. The proposed filters that used FSCS technique and a broadband stop filter is integrated to band pass filter to suppress the harmonics. The BSF are also placed between stubs so that the size is larger than prevent as compared to conventional one. The propose filters have center frequency of 5.8 GHz, bandwidth of 50% and harmonics suppressin is 120% has in bandwith. The measurement results in the case of ${\lambda}_g/4$ short stub filter, insertion loss of 0.5 dB, return loss of 14 dB are achieved and in the case of ${\lambda}_g/2$ open stub filter, loss of 0.8 dB, return loss of 14.4 dB are achieved. The simulation results and the measurement results are almost the same.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.2A
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• pp.167-173
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• 2008

In this paper, the flexible narrow bandpass filters (BPFs) with ${\lambda}$g/4 short and ${\lambda}$g/2 open stubs by microstrip line on duroid substrate are suggested. These BPFs with narrow bandwidth show flexible bandwidth with variation of the position of the stubs using the Qe (external quality factor) without changing the impedance value at microwave range. On the other hand, by replacing the series quarter-wavelength connecting lines with the equivalent T-shaped line of bandstop filter(BSF), the compact stub bandpass filter with harmonics suppression can be realized. The BPF with ${\lambda}$g/4 short stubs shows the insertion loss of 2.1 dB and the return loss of 18 dB and BPF with ${\lambda}$g/2 open stubs shows the insertion loss of 1.2 dB and the return loss of 21.9 dB at the center frequency of 5.8 GHz and the bandwidth of 10 %.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.6
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• pp.37-43
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• 2013

In this paper, an UWB (Ultra Wide Band) band-pass filter with open stubs using SIR (Stepped Impedance Resonator) structure is presented. The proposed band pass filter (BPF) has SIR structure instead of open stubs for UWB application with low insertion loss. The bandwidth of the proposed BPF is 103 % at the center frequency of 5.8GHz and the insertion and return losses are 0.17dB and 13.1dB, respectively. Also, the entire size of the proposed band-pass filter is $21.6{\times}17.8mm^2$.

• ETRI Journal
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• v.30 no.4
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• pp.615-617
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• 2008

A novel and compact elliptic-function bandpass filter is proposed in this letter. The techniques of slot etching and the addition of open stubs are applied to enhance the self-inductance and self-capacitance of hexagonal open-loop resonators. Thus, size reduction and improved transmission performance are obtained. Compared to the performance of the conventional design, the central frequency and insertion loss are reduced by 28% and 3.1 dB, respectively. Measurements show that the proposed filter has a fraction bandwidth of 23% at the central frequency of 1.84 GHz, and its insertion loss in the passband is less than -1.5 dB. The bandpass filter occupies only 12 mm${\times}$21.2 mm (approximately $0.24{\lambda}_g{\times}0.14{\lambda}_g$).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.4
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• pp.323-332
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• 2009

In this paper, we introduce a modified short-circuited stub bandpass filter suitable for ultra-wideband(UWB) applications utilizing low temperature co-fired ceramic(LTCC) technology. By modifying the conventional short-circuited stub bandpass filter structure with stubs and connecting lines of lower characteristic impedances, the number of stubs has been reduced from 5 to 2 on a high dielectric constant substrate($\varepsilon_r$ = 40). A wireless local area network (WLAN) stopband in the frequency range of 5.15 to 5.825 GHz has been inserted into the filter characteristic using three short-circuited coupled lines. The filter has been measured with an insertion loss less than 1.0 dB and return loss better than 10 dB in the pass bands. A bandwidth ratio of 109.49 % has been achieved. Measurement results agree well with simulation results. The dimensions of the filter are $4{\times}8{\times}0.57\;mm^3$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.5
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• pp.486-493
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• 2010

This article introduces a novel ultra wideband(UWB) bandpass filter(BPF) with sharp roll-off characteristics in stripline structure. The UWB characteristic is basically obtained from capacitive coupled cross resonator. The resonator has ${\lambda}/2$ length. And at the center of the resonator, two stubs are loaded, one is a ${\lambda}/8$ short-circuited stub and the other is a ${\lambda}/8$ open-circuited stub. The two stubs provide two attenuation poles at lower and upper cutoff frequencies. For input and output lines, two identical capacitively coupled lines have been installed to suppress the unwanted signals in the lower and upper stopbands. The filter has been designed for the U.S. UWB band(3.1~10.6 GHz) with two transmission zeros at 2.4 and 11.1 GHz. The filter has been realized with Low Temperature Core-fired Ceramic(LTCC) green tape which has the dielectric constant of 7.8. Measurement results agree well with HFSS simulation results. Insertion loss less than 0.7 dB and return loss better than 14 dB in the pass band have been measured. The group delay in the center frequency is 0.27 ns and the group delay variation within pass band is less than 0.5 ns. The size of the filter is $6{\times}18{\times}0.6\;mm^3$.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.5
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• pp.69-74
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• 2010

In this paper, we proposed a compact arbitrary dual-band band-stop filter using CRLH transmission line. The proposed filter used CRLH transmission line as stub and it developed dual-band band-stop characteristics using non-linear phase response of CRLH transmission line. The size of proposed filter is compact. And it can control arbitrary dual stop band. In this paper, designed band-stop filter at GPS band and ISM band As result, the S(2,1) is about -30dB at GPS band and about -29dB at ISM band. The fabricated filter is very compact. Its dimension is 10mm*15mm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.2A
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• pp.147-152
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• 2005

In this paper, we have proposed a novel DGS(Defected Ground Structure) resonator and has designed the band -pass filter using the proposed ${\subset}$ stub-I type DGS resonator. This structure has strong advantages that can vary the retune loss at the passband freely and also can easily tune the attenuation pole frequency at the stopband. The bandpass filter can be made more smaller than the existing filters and be used to find the various applications for eliminating the harmonics and spurious mode at IMT-2000 band.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.7
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• pp.65-70
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• 2012

In this paper, a compact UWB (Ultra Wideband) BPF(Band-Pass Filter) with dual notched bands is proposed using a hybrid Composited Right-Left Handed (CRLH) and Defected Ground Structure (DGS). To avoid the interferences such as Wireless LAN (Center frequency: 2.4GHz and 5.8GHz), the CRLH is employed to obtain the dual notched bands and the DGS is used to obtain the wide stop-band above the pass-band. The fabricated filter has good performance and has more than 30dB rejection at the center frequency of 2.4 GHz and 5.8GHz. The dual notched bands are easily movable by changing the CRLH parameter. Also the insertion loss is less than 0.4dB in the lower pass-band and 0.7dB in the upper pass-band, and it has small group delay variation less than 0.6ns. The size of the fabricated filter is very compact (17mm*17mm).