• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2001.11a
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• pp.194-197
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• 2001

본 논문에서는 결합창으로 결합을 구현한 유전체 공진기 필터의 결합창 특성을 해석하였다. 결합창의 특성을 결합계수로 표현하였으며, 간단한 표현식으로 유도하였다. 결합창의 크기를 변화시키면서 해석 방법을 적용하여 결합계수를 계산하였고, 측정결과와 비교하여 해석의 유효성을 증명하였다. 본 논문에서 제안한 방법은 적용이 간단할 뿐 아니라, 결합창의 제작 및 측정오차 범위에서 정확한 결과를 보였다. 본 논문에서 제안한 방법은 유전체 공진기 필터의 설계 및 유전체 공진기와 Varactor diode로 이루어지는 동조필터가 동조주파수 대역에서 일정한 통과대역폭을 가지기 위한 최적화된 결합창의 설계적용이 가능하다.

• Journal of the Optical Society of Korea
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• v.19 no.6
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• pp.665-672
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• 2015

We demonstrate an ultrathin metamaterial for polarization independent perfect absorption as well as a band-pass filter (BPF) which works at a higher frequency band compared to the perfect absorption band. The planar metamaterial is comprised of three layers, symmetric split ring resonators (SSRRs) at the front and structured ground plane (SGP) at the back separated by a dielectric layer. The perfect metamaterial absorber (MA) can realize near 100% absorption due to high electromagnetic losses from the electric and/or magnetic resonances within a certain frequency band. The thickness of the structure is only 1/28 of the maximum absorption wavelength.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.5
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• pp.715-722
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• 2000

In this paper, the PLDRO is designed and implemented for X-band. It is comprised of tunable high Q resonator with a varactor diode for frequency tuning, loop filter and a 1/8 prescaler which up to 10GHz. Also, it is implemented a TCXO and a VCO signal into the phase detector and achieved a highly stable signal source. From the measurement, the designed PLDRO has the output power of 2.5dBm at 8GHz and phase noise of -64.33dBc at 10KHz offset from carrier. Its characteristic is 26 dBc. This PLDRO has much better temperature stability.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.9
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• pp.931-935
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• 2003

A multilayer two-stage LC bandpass filter using low-temperature cofired-ceramic(LTCC) is proposed in this paper. The proposed bandpass filter is composed of two ceramic substrates with different dielectric constant instead of single ceramic material from top to bottom layer. Inductive elements are designed in a low permitivity ceramic layer to reduce parasitic effects and loss, while capacitive elements are designed in a high permitivity ceramic layer for size reduction. The proposed filter has 950 MHz center &equency, 118 MHz tractional bandwidth, and 3.5 dB insertion loss. And, the total size of this filter is 2.5${\times}$2.5${\times}$l.4mm$^3$. The performance of filter is analyzed by changing coupling capacitance between each resonator.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.55-56
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• 2018

In this paper, a method for analyzing the dielectric constant of a planar substrate is proposed. To this end, a band-stop filter was created by adding a H-shaped resonant aperture to the ground plane of a microstrip transmission line. A planar substrate of 2 mm thickness was placed behind the ground plane of the microstrip transmission line and the change of the resonant frequency with the change of the dielectric constant of the substrate was investigated. It can be seen that the change ratio of the frequency to the reference resonant frequency is larger than that of the conventional complementary split ring resonator structure.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.8
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• pp.1313-1321
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• 2000

This paper presents a novel HTS microstrip pseudo-lumped element resonator for the compact and simple filter design. A 7-pole bandpass filter with quasi-elliptic response is designed and fabricated using non-adjacent couplings between resonators. A seven-pole quasi-elliptic filter is fabricated using double sided YBCO on a LaAlO$_3$ substrate with thickness of 0.5 mm and dielectric constant of 23.5. The filter has an insertion loss of 0.8 dB at 20K, a bandwidth of 8 MHz at the center frequency of 1774 MHz, and an attenuation of 33 dB for the cut-off-band of 1 MHz.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.578-581
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• 2004

유전체가 삽입된 공동 공진기는 유전체에 대부분의 전자계가 집속되어 있기 때문에, 도체 손실이 매우 적고 높은 Q값과 온도 안정성이 뛰어나다. 동일한 주파수에서 동작하는 다른 필터에 비해 상대적으로 작기 때문에 소형화에도 적합하다. 본 논문에서는 유전체가 삽입된 공동 공진기의 전자기 분포와 특성을 수치해석과 HFSS(High Frequency Structure Simulator)를 이용하여 분석하였고 이 결과를 토대로 HFSS를 이용한 순차적 방법을 도입하여 4-pole 이중모드 대역통과 필터를 설계, 제작하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.4
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• pp.369-376
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• 2003

In this paper, Ka-Band NRD guide band pass filter with newly designed inductive post structure is proposed and analyzed with its test results. Generally, millimeter-wave filters are very sensitive in their physical dimensions, hence, it is requires extreme precisions of several micron so as to get the designed performance. In case of common NRD Guide filter with air gap coupled structure, it is fabricated with dielectric blocks coupled via air gap. In these structures, however, it was not easy to fabricate and to process of each NRD guide dielectric resonator blocks using PTFE, so it was almost impossible to assemble with several microns in precision. In this our research, however, each dielectric resonators are coupled with a pair of inductive metal post, so all resonators are located in a single NRD Guide. The dielectric parts between two pairs of posts are operated as resonators of each stage, and the positions of the post decide the couplings between resonators. The structure we suggested is suitable fur mass production, because it is very simple and easy to process. As a result of measurements, designed NRD guide inductive post filter has a superior performance. The center frequency is 39.475 GHz with 350 MHz bandwidth, insertion loss is less than 1.8 dB, and the return loss is below than -18 dB.

• Journal of information and communication convergence engineering
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• v.11 no.1
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• pp.45-49
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• 2013

A compact radio frequency (RF) bandpass filter (BPF) in low temperature co-fired ceramic (LTCC) is suggested for WiMAX applications. The center frequency ($f_0$) of the BPF is 5.5 GHz and its pass band or 3-dB bandwidth is 700 MHz to cover all the three major bands, low and middle unlicensed national information infrastructure (U-NII; 5.15-5.35 GHz), World Radiocommunication Conference (5.47-5.725 GHz), and upper U-NII/industrial, scientific, and medical (ISM) (5.725-5.85 GHz), for the WiMAX frequency band. A lumped circuit element design-the 5th order capacitively coupled Chebyshev BPF topology-is adopted. In order to design a compact RF BPF, a very thin ($43.18{\mu}m$) ceramic layer is used in LTCC substrate. An interdigital BPF is also designed in silicon substrate to compare the size and performance of the lumped circuit element BPF. Due to the high relative dielectric constant (${\varepsilon}_r$ = 11.9) of the silicon substrate, the quarter-wavelength resonator of the interdigital BPF can be reduced. In comparison to the 5th order interdigital BPF at $f_0$ = 5.5 GHz, the lumped element design is 24% smaller in volume and has 17 and 7 dB better attenuation characteristics at $f_0{\pm}0.75$ GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.10
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• pp.996-1003
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• 2003

There are critical drawbacks in fabricating MMIC transversal filters because the length of the conventional transversal filter structure is much longer than the width. In order to solve this structural problem, a transversal filter using multiple-coupled-line directional couplers which can achieve tight coupling is proposed. The length of the proposed transversal filter can be made short using multiple-coupled-line couplers so that the structure of the proposed filter is applicable to MMIC technology. Because of the dielectric and conductor losses, the excited signal at the input port becomes smaller when it progresses through each directional coupler. Therefore, the strength of the coupled signals at the latter directional couplers becomes smaller than the designed one and this, in turn, gives rise to performance aggravation. A modified coupling coefficient formula to prevent frequency characteristic degradation is introduced. The proposed filter structure and the design method are verified by the calculated result and 3D full-wave analysis.