• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.19 no.10
• /
• pp.1122-1128
• /
• 2008

A novel tunable bandstop filter was proposed. It is composed of a right-handed transmission line, which has lowpass characteristics, and a left-handed transmission line which has highpass characteristics. Dispersion relations for the unit cells of RHTL and LHTL were derived by the method of ABCD parameter analysis. Varactor diodes and chip inductors were used to make the unit cells of RHTL and LHTL. A tunable bandstop filter was designed and fabricated by the parallel connection of RHTL and LHTL. The measured results of the proposed tunable bandstop filter are agreed well with the simulated results.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.39 no.9
• /
• pp.35-43
• /
• 2002

In this paper, microstrip ring with a narrow gap is characterized and used as a tunable microwave bandgap (MBG) structure. The center frequency of MBG is mainly determined by the mean circumference of the ring and coincides with odd mode resonance frequency of the ring resonator. The stop band formation by the proposed microstip MBG ring is due to the reflection of electromagnetic waves at the narrow gap introduced in the ring, and the reactive component mounted on the gap makes the stop band vary according to its value. The mounting of capacitor (inductor) is observed to decrease (increase) the center frequency of the stop band. The varactor-mounted microstrip MBG ring is expected to be useful in microwave switches and microwave amplifier circuits.

• The Journal of the Korea Contents Association
• /
• v.9 no.12
• /
• pp.566-571
• /
• 2009

In this paper, microstrip bandpass filter combined DCRLH metameterial-cells with a hairpin resonator is designed and fabricated to be transferred only fundamental passband signal, and removed a spurious resonant mode occurring when filter design using a microstrip transmission line is done. The bandpass filter is composed of CCRLH hairpin resonator and DCRLH interdigit metameterial-cells. The hairpin resonator with CCRLH property is implemented between two DCRLH interdigit metameterial-cells with DCRLH property, which is parallel to input port and output port. The interdigit metameterial-cells suppress spurious harmonics occurring on the higher order frequency and improve a filter performance. Insertion loss of the fabricated microstrip bandpass filter on the passband from 1.91GHz to 2.41GHz is 0.2dB, and attenuation on the stopband from 3GHz to 7.7GHz is bellower than -30dB. Therefore, this filter has a good performance for both mobile communications of WCDMA and wireless internet of WiBro.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.3
• /
• pp.1734-1739
• /
• 2014

In this paper, microstrip low pass filter using transmission line with the modified DCRLH structure is designed and fabricated to be removed a spurious resonant mode, and a deep attenuation in stop band. The low pass filter is composed of shunt open-stub to get a deep attenuation and series short-stub to eliminate the spurious harmonics in stop band. In this way, the spurious harmonics occurring on the higher order frequency are suppressed and the filter performance is improved. Insertion loss and VSWR of the fabricated microstrip low pass filter in the passband from DC to 1.5 GHz is 1.26 dB and 1.65, and attenuation on the stopband from 1.84 GHz to 2.18 GHz is less than -100 dB. And also this filter has a good performance for 20 watt power test.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.21 no.1
• /
• pp.28-35
• /
• 2010

In this paper, we designed and fabricated a ultra-wideband(UWB) bandpass filter with a good performance of a stopband, and a notched band in passband. The transformed equivalent circuit of the highpass filter was realized by distributed element. A wide-passband with 3-dB fractional bandwidth of more than 100 % was achieved by using optimum response of the HPF. For improving lower and upper stopband characteristic, a cross coupling between feed lines was employed, which was analyzed by desegmentation technique. In order to reject interference of Wireless LAN and Hyper LAN(5.15~5.825 GHz), the narrow notched(rejection) band was realized by a spurline. The fabricated BPF indicated the passband from 3.1 to 10.55 GHz and the flat group delay of less than 0.94 ns over the entire passband except the rejection band. The filter shown sharp attenuation both inside and outside the band and notched band from 5.2 to 6.12 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.22 no.3
• /
• pp.275-281
• /
• 2011

In this paper, we proposed the small planar monopole antenna with modified ground plane for UWB communications. The proposed antenna not only shows Ultra-Wideband characteristic(3.1~10.6 GHz) suitable for UWB communications but has partially notched-band characteristic to reject 5 GHz WLAN band(5.15~5.35 GHz, 5.470~5.825 GHz). The proposed antenna improved impedance matching through two slits on ground plane, and the rejection band was induced by two ${\lambda}$/4 open stubs on center of two slits. Fabricated antenna satisfied VSWR${\leq}$2 in 2.88~10.83 GHz except for the band rejection of 5.08~5.83 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.13 no.10
• /
• pp.1071-1077
• /
• 2002

In this paper, we have studied the dependence of insertion loss of the pressed microstrip PBG ring consisting of coupled two microstrip lines. When the distance decreases, two or three attenuation poles are created by the coupling between the lines. Thus the pressed PBG ring exhibits a wide stop band and sharp cutoff characteristics.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.13 no.2
• /
• pp.136-145
• /
• 2002

In this paper, we facilitate the analysis of 1D PBG structure using a ABCD matrix formulation after converting field parameters into circuit parameters. Dispersion diagrams for an infinite 1D PBG structure are derived and compared with the frequency responses for a finite structure (N=10). When the proposed method is adopted, the analysis and synthesis of 1D PBG structures become very convenient.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.17 no.2 s.105
• /
• pp.89-94
• /
• 2006

A compact microstrip band-selective filter for ultra-wideband(UWB) radio system is proposed. The filter combines the traditional short-circuited stub highpass filter and coupled resonator band-stop filter on both sides of the mitered 50-ohm microstrip line. To realize the pseudo-highpass filtering characteristic over UWB frequency band(3.1 GHz to 10.6 GHz), a distributed highpass filter scheme is adopted. Three coupled resonators are utilized to obtain the band stop function at the desired frequency band. By meandering the coupled resonators, there is $29\;\%$ size reduction in footprint compared to the traditional band-stop filter using L-shaped resonators. The measured results show that the filter has a wide passband of $146.7\;\%$(2.1 GHz to 10.15 GHz) with low insertion loss and the stop band of $10.04\;\%$(5.2 GHz to 5.75 GHz) for 3-dB bandwidth. The measured group delay is less than 0.7 ns within the passband except the rejection band.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.47 no.8
• /
• pp.68-73
• /
• 2010

In this paper, a compact Ultra-Wideband band-pass filter with notched band at 5.8GHz by using LC resonator is proposed. The structure of the proposed band-pass filter is very simple, and the DGS(Defected Ground Structure) is used to get the low-pass filter characteristics and the LC resonator is used to get the notched filter. The proposed band-pass filter can be much smaller than a cascaded filter type. The LC resonator is designed with a radial stub and small stub. As a result of measurement, the insertion loss is less than 0.5dB throughout the pass-band of 2.21GHz~10.92GHz, the return loss is more than 16dB and the maximum variation of group delay is 0.29ns and a notched band is 5.2GHz~6.2GHz.