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A 3‐20GHz Vivaldi Antenna with Modified Edge
Bieng-Chearl Ahn, Otgonbaatar Gombo 충북대학교 컴퓨터정보통신연구소 2013 컴퓨터정보통신연구 Vol.21 No.1
A wideband elliptically-tapered-aperture Vivaldi antenna is proposed in this paper. The tapered aperture improves the lowfrequency impedance matching. The antenna is printed on a Teflon substrate and fed by a microstrip line. The size of the antenna is 92.9mm x 100.4mm x 0.787mm. The design, fabrication and measurement of the proposed antenna are presented.
A Fast Battery Charger for USN Applications
Otgonbaatar Gombo, Bieng-Chearl Ahn 충북대학교 컴퓨터정보통신연구소 2013 컴퓨터정보통신연구 Vol.21 No.1
This paper presents an implementation of a supercapacitor-based fast battery charger for USN sensor nodes. Our goal is to charge the sensor node battery in as short as possible time. In order to shorten the charging time, we first charge a pack of supercapacitors, which will slowly charge a battery in the sensor node. The implemented charging system consists of two parts, a portable charger and a battery unit. The portable charger includes a 200-F pack of supercapacitors and two supercapacitor chargers. The battery unit includes a 400-F pack of supercapacitors, a step-up converter, a lithium battery charger and a lithium battery. The supercapacitor packs in the portable charger and the battery unit are charged up to 10V and 5V respectively. The sensor node battery unit can be charged in 6 minutes.
박영규(Young-Kyu Park),노준우(Joon-Woo Noh),안병철(Bieng-Chearl, Ahn) 한국정보기술학회 2018 한국정보기술학회논문지 Vol.16 No.3
This paper presents a circularly-polarized crossed dipole for use in the feed of a C-band telemetry tracking reflector antenna. The proposed dipole is of printed type and fed by a microstrip line with an integrated balun. The crossed dipole is optimally designed by iterative adjustments of design parameters. The designed crossed dipole has reflection coefficient of less than -15dB at 4.8-5.6GHz, and at 5.12GHz, gain of 10dBic, axial ratio of 1.0-3.9dB and gain taper of 9.7dB within 64° from the beam axis. Five units of the designed crossed dipole are placed on a 136-mm diameter ground plane to design a monopulse feed for a prime-focus monopulse reflector antenna with F/D of 0.4. The sum pattern of the designed feed is nearly same as that of a single crossed dipole, and azimuth and elevation difference patterns have gain of 10.6dBic, axial ratio of 1.7-6.9dB, gain taper of 8dB, and null gain of -30dBic. The performance of the designed feed has been verified by applying it to a 1300-mm diameter reflector antenna with a focal length of 520mm.
인쇄형 다이폴을 이용한 Ku-대역 원형도파관-동축선 변환부 설계
윤제영(Je-Young Yun),노준우(Joon-Woo Nho),이찬호(Chan-Ho Lee),박영규(Young-Gyu Park),안병철(Bieng-Chearl Ahn) 한국정보기술학회 2017 한국정보기술학회논문지 Vol.15 No.7
Circular waveguides are widely used in the realization of reflector-antenna feeds, orthomode transducers, polarizers, filters/multiplexers, and rotary joints. A circular waveguide to coaxial cable transition is often employed to connect a circular waveguide to a transmitter/receiver. This paper presents an in-line circular waveguide to coaxial cable transition employing a printed dipole. The proposed transition consists of a shorted circular waveguide, a microstrip feed line, a microstrip balun, a printed dipole, a parasitic element for wideband operation, and a coaxial probe. Change in the reflection coefficient of the transition versus design parameters is analyzed, from which an optimum design is obtained. Designed transition is fabricated and it reflection coefficient is measured and compared with the simulation. The proposed transition shows reflection coefficient of less than -15dB and higher-order mode levels of less than -20dB at 13.4~17.2GHz.