A Method for Improving Stopband Characteristics of a Dual-Band Filter

Jahyeon Lee,Yeongseog Lim 한국전자파학회JEES 2011 Journal of Electromagnetic Engineering and Science Vol.11 No.3

This paper presents a simple and effective method for improving stopband rejection characteristics of previously studied dual-band filters. Small electric couplings were applied to the symmetrically positioned shunt resonators, which divided each transmission zero into two transmission zeros without any effect on passbands. We were able to achieve improved stopband rejection characteristics by these additional transmission zeros. For the filter application, we designed a dual-band filter with improved stopband characteristics using microstrip quasi-lumped elements. The electric couplings that control the location of transmission zeros are controlled by the distance between symmetric open stubs of the filter. The filter was fabricated with a relative dielectric constant of 3.5 and a thickness of 0.76 ㎜. The fabricated filter has a small size (14.6×13.2×0.76 ㎜) and a low insertion loss when compared with conventional filters.

Design of Coaxial Slot-Sleeve Type Applicator

Sooman Park,Yeongseog Lim 한국통신학회 2005 한국통신학회 학술대회논문집 Vol.2005 No.6

Broadband flexible meander line antenna with vertical lines

Jung, Jinwoo,Lee, Hyeonjin,Lim, Yeongseog Wiley Subscription Services, Inc., A Wiley Company 2007 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS Vol.49 No.8

<P>A novel broadband meander-line antenna with vertical lines is presented. The proposed antenna has a broadband impedance bandwidth of ∼785 MHz, which covers DCS, PCS, UMTS, WiBro, and WLAN bands. For frequencies across the operating bands, the proposed antenna displays omni-directional radiation patterns. The proposed antenna has compact dimensions of 12 × 23.1 mm<SUP>2</SUP>. The antenna is flexible due to the F-PCB material used. For these reasons, a cylindrical and folded structure is presented, as transformed from planar. Experimental results using the constructed prototype are presented and discussed. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1984–1987, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22564</P>

Array of Slot - Sleeve Antennas for Hyperthermia Therapy

Soo-Man Park,Yeongseog Lim 한국전자파학회JEES 2005 Journal of Electromagnetic Engineering and Science Vol.5 No.3

To increase the efficiency of an applicator during microwave hyperthermia therapy, first, the length from the antenna end to a slot is varied to get the optimal matching of the characteristic impedance at the frequency of 2.45 GHz. Using the electric and thermal constants of biological tissue, we compose a phantom to calculate temperature increment as well as the resonance characteristics and the SAR distributions.<br/> The proposed 3-slot sleeve antenna inserted in an applicator plays an effective role in increasing the therapy size in the view of heating performance as electromagnetic energy tends to concentrate on not feed point direction but treatment area. The SAR is then used in combination with a finite difference heat transfer equation to determine the temperature distribution. Also, in order to shorten treatment time and increase therapy size, a square-array structure is suggested and analyzed.

Analyzing impedance characteristics of monopole antennas with different chassis widths for dual resonance-based broadband operation

Jung, Jinwoo,Lee, Hyeonjin,Lim, Yeongseog Wiley Subscription Services, Inc., A Wiley Company 2010 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS Vol.52 No.4

<P>Variation of the impedance characteristics between two monopole antennas, according to the width of chassis is analyzed. Dual resonance-based broadband antennas are proposed on the basis of the analyzed results. The experimental antennas are an inverted L-shaped monopole antenna and a printed meander line monopole antenna. The dimensions of the derived antennas with a chassis are appropriate for a USB dongle application. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:981–984, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25082</P>

하나의 이중 모드 공진기를 이용한 대역 통과 필터 설계

안재민(Jaemin An),임영석(Yeongseog Lim) 한국전자파학회 2010 한국전자파학회논문지 Vol.21 No.12

본 논문에서는 하나의 이중 모드 공진기를 이용한 대역 통과 필터의 새로운 설계 방법을 제안한다. 제안한 설계 방법은 이중 모드 공진기를 두 개의 단일 공진기로 보고 공진기 사이의 결합 계수를 구하여, 이를 바탕으로 이중 모드 공진기의 두 공진 주파수를 계산한 후 필터 전송 영점의 위치에 따라 각각 배치하였다. 제안한 설계방법을 검증하기 위해, E-모양의 이중 모드 공진기를 이용하여 WLAN 서비스 대역을 만족하고, 전송 영점이 각각 상측과 하측에 위치하는 대역 통과 필터를 설계?제작하였다. This paper proposes a new design method of bandpass filter with single dual-mode resonator. In the proposed method, a coupling coefficient between two resonators was obtained by considering a dual-mode resonator as two single resonators. Based on the obtained coupling coefficient, two resonant frequencies of dual-mode resonator were calculated and then arranged according to a transmission zero's location of required filter. To verify the proposed theory, two WLAN bandpass filters which have a transmission zero to a lower and an upper stopband repectively were designed and implemented.

기생 요소 효과들을 고려한 얇은 두께의 LTCC 저역 통과 필터 설계

김유선(Yuseon Kim),임영석(Yeongseog Lim) 대한전자공학회 2008 電子工學會論文誌-TC (Telecommunications) Vol.45 No.12

본 논문에서는 LTCC(low temperature co-fired ceramic) 공정을 이용한 삽입된 수동 소자들을 갖는 필터 설계를 하였다. 우수한 성능과 소형화를 위해서 제안된 적층 구조의 기생 성분들은 제안된 회로 변환 과정을 통해 전체 필터 회로에서 긍정적인 효과를 갖도록 하였다. 그 결과 소형화된 저역 통과 필터는 다른 논문들의 소형화된 구조들에 비해 50프로 이상의 적은 두께를 갖을 뿐만 아니라 0.5 ㎓와 5 ㎓ 사이에서 이상적인 저역 통과 필터의 응답을 보였다. This paper presents a filter design technique with the embedded passive elements using the low temperature co-fired ceramic (LTCC) process. For the high performance and size reduction, the parasitic elements of the proposed multi-layer structure are positively considered by using the proposed circuit transformation procedures. As a result, the compact low pass filter (LPF) not only has at least 50% more compact thickness than other reported compact structures, but also provides ideal LPF response between 0.5㎓ and 5㎓.

Compact modified trapezoid-shaped ultra-wideband antenna with parasitic loops

Jung, Jinwoo,Lee, Hyeonjin,Lim, Yeongseog Wiley Subscription Services, Inc., A Wiley Company 2009 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS Vol.51 No.5

<P>A modified trapezoid-shaped monopole antenna for ultra-wideband operation having compact dimensions (12.7 × 22.5 × 1.6 mm<SUP>3</SUP>) is proposed. With a modified trapezoid radiator and parasitic loops, the proposed antenna has a very wide impedance bandwidth measured at 8.41 GHz (3.06–11.47 GHz, defined by 2:1 VSWR). The group delay, phase, and transmission loss are also measured and discussed. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1261–1263, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24313</P>

이중 모드 공진기를 이용한 이중 대역 대역 통과 필터 설계

이자현(Jahyeon Lee),임영석(Yeongseog Lim) 한국전자파학회 2011 한국전자파학회논문지 Vol.22 No.2

본 논문에서는 설계 방법이 단순하면서 통과 대역의 대역폭 조절이 독립적으로 가능한 소형의 이중 대역 대역 통과 필터를 제안하였다. 각각의 통과 대역은 서로 다른 두 개의 이중 모드 공진기를 이용하여 독립적으로 설계하였다. 제안된 이중 대역 대역 통과 필터는 세 개의 전송 영점을 갖는다. 두 개의 전송 영점은 각각의 이중 모드 공진기에서 발생하며, 입출력 선로 간의 결합 효과에 의해 추가적으로 하나의 전송 영점이 발생한다. 제안된 이중 대역 대역 통과 필터 설계 방법을 이용하여 2.4/5.7 ㎓ WLAN에 동작하는 이중 대역 대역 통과 필터를 설계 및 제작하였다. A compact microstrip dual-band bandpass filter with controllable bandwidth for each passband is proposed. Each passband is independently designed using two different dual-mode resonators. The proposed dual-band bandpass filter has three transmission zeros. Two transmission zeros are generated by each dual-mode resonator. An additional transmission zero is generated by input/output port coupling. The dual-band bandpass filter application is designed for 2.4/5.7 ㎓ WLAN. Experimental results are presented to validate theory.

위상 배열 추적 안테나 시스템의 추적 방법에 관한 연구

정진우(Jinwoo Jung),임영석(Yeongseog Lim) 대한전자공학회 2018 전자공학회논문지 Vol.55 No.7

통신 데이터링크 구축을 위한 위상 배열 추적 안테나 시스템의 추적 방법에 관하여 연구하였다. 추적 시스템의 추적 절차는 초기 빔 형성, 추적, 그리고 예측 추적으로 구분하였다. 초기 빔 형성은 표적의 위치를 인지하지 않은 상태에서 통신을 위한 원활한 빔을 형성하는 절차로, 이동 표적을 대상으로 최적의 위상 천이 조합을 원활하게 탐색하기 위한 개선된 개체 군집 최적화 알고리즘을 사용하였다. 추적은 초기 빔 형성 이후, 이동 표적을 지속적으로 지향하는 빔을 형성하는 절차로, 원활한 추적을 위해 위상 천이 값 누적을 기반으로 한 순차 로빙 추적과 알파-베타 필터를 사용하였다. 예측 추적은 표적의 이동 중 지형 및 지물에 의해 표적과 추적 시스템 사이의 가시선이 간헐적으로 차단될 경우에 대응하여 표적 위치를 예측하여 추적을 수행하는 절차로, 단절 이후 원활하고 연속적인 재 추적을 위해 알파-베타 필터를 사용하였다. Tracking method of phased array antenna system for communication data link construction was studied. Tracking procedures in the tracking system are divided into initial beam-forming, tracking, and predictive tracking. In procedure of a initial beam forming, the improved particle swarm optimization algorithm was used to search the optimum phased set for moving target. In procedure of a tracking, the sequential lobing with alpha-beta filter based on phase accumulation was used for smoothing tracking. A prediction tracking is procedure for the case of non line of sight between moving target and a tracking system, alpha-beta filter was used for smooth and continuous re-tracking after disconnection.