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박진석(Jae-Hoon Bang),김기록(Ki-Rock Kim),이제선(Jea-sun Lee),방재훈(Jae-Hoon Bang),안병철(Bierng-Chearl Ahn),전종훈(Jong-Hoon Chun) 한국정보기술학회 2009 한국정보기술학회논문지 Vol.7 No.6
In this paper, we design, fabricate and test a 35㎓ waveguide monopulse comparator for use in a tracking radar. The proposed comparator is consisted of four 180° E-plane ring hybrid couplers placed on a single plane. The comparator has four input ports mating with a monopulse feed horn and three output ports corresponding to the sum, azimuth and elevation difference channels. Waveguide sections and bends are utilized in connecting input and output waveguides to the comparator. The whole structure is fabricated in three pieces using the widely-used split-block waveguide machining techniques. Measurements of the fabricated comparator show reflection coefficient less than -20㏈, amplitude balance better than ±0.6㏈, phase balance better than ±5° at all channels, which are in good agreement with simulations.
임재홍(Jae-Hong Lim),왕가남(Jianan Wang),이주(Shu Li),방재훈(Jae-Hoon Bang),안병철(Bireng-Chearl Ahn) 한국정보기술학회 2016 한국정보기술학회논문지 Vol.14 No.1
In this letter, a broadband circularly-polarized antenna is proposed for UHF RFID applications. The proposed antenna consists of three substrates, a metal cavity and four metal posts. The parasitic patch and radiation patch are realized on the upper and intermediate substrates, respectively. The 50-Ω feeding line puts on the lower substrate and provides successive 90° phase delays to the radiating patch through four metal posts. The width of the feeding line and a size of the radiating patch are firstly calculated with respect to the equivalent dielectric constant obtained from the commercial software. The optimally designed dimensions of the proposed antenna are obtained from the parametric studies. The optimally designed antenna is fabricated and measured to confirm its performances. Measurements show that the fabricated antenna has a reflection coefficient of less than -10dB over 735-979MHz, an axial ratio less than 5dB over 760-930MHz.
이제선(Jae-Sun Lee),서윤덕(Yoon-Dug Seo),이순천(Soon-Chun Lee),방재훈(Jae-Hoon Bang),안병철(Bierng-Chearl Ahn) 한국정보기술학회 2010 한국정보기술학회논문지 Vol.8 No.8
In this paper, we propose a dielectric chip antenna with its metal patterns printed on a circuit board. In a typical dielectric chip antenna, metal patterns are formed on the surface or interior of a material block of high dielectric constant. In this paper, metal patterns of a dielectric chip antenna are printed on the circuit board where the chip antenna is to be mounted, and a dielectric material block is placed on top of metal patterns, resulting in a low-cost dielectric chip antenna structure. Antenna electrode patterns are printed on a 33×30㎜ FR-4 substrate, which are then covered with a dielectric material of size 12×5×0.4㎜ and dielectric constant 22, resulting in a structure equivalent to a dielectric chip antenna with metal patterns formed on the bottom surface. The optimum design of the antenna is obtained using a commercial software. The designed antenna is fabricated and tested. The fabricated antenna shows a reflection coefficient less than -10㏈ over 225㎒ bandwidth centered at 2.45㎓, a maximum gain of 1.98㏈i, an average gain of -0.19㏈i, and a maximum- to-minimum gain difference of 9.98㏈.
윤금노(Keum-No Yoon),방재훈(Jae-Hoon Bang),오트건바타르 검보(Otgonbataar Gombo),안병철(Bierng-Chearl Ahn),김상기(Sang-Ki Kim) 한국정보기술학회 2012 한국정보기술학회논문지 Vol.10 No.1
The cylindrical near-field measurement system is widely used for the measurement of antennas with a sharp beam in one plane and a broad one in the other. In this paper a method is proposed for the implementation of a cylindrical near-field measurement system based on a personal computer. The proposed near-field system consists of an anechoic chamber, an antenna rotator, a probe and its scanner, a system controller, a network analyzer, and a system operating program. The near field of the antenna under test (AUT) is measured at constant intervals on a cylindrical surface enclosing the AUT, from which far-zone fields, gain, and radiation patterns of the AUT are obtained. An efficient fast Fourier transform technique is employed for the conversion of the near-zone electric field into the far-zone one. The implemented cylindrical near-field system is employed to measure the characteristics of an X-band horn antenna and a waveguide slot array and its accuracy is verified by comparison with the far-field measurement.
밀리미터파 대역 도파관-마이크로스트립 변환부 설계 및 제작
함우형(Woo-Hyung Ham),방재훈(Jae-Hoon Bang),안병철(Bierng-Chearl Ahn),정명숙(Myung-Sook Jung),노진입(Jin-Yip Roh) 한국정보기술학회 2009 한국정보기술학회논문지 Vol.7 No.6
We report a waveguide-to-microstrip transition based a probe structure for use in millimeter-wave RF modules. The proposed waveguide-to-microstrip transition is composed of a microstrip probe and a rectangular waveguide. The microstripline is realized using a low-loss substrate made of pure teflon. Design parameters of the transition are optimized using numerical simulation. The fabricated back-to-back transition exhibits reflection coefficient of -24 ㏈ and transmission coefficient of -0.4 ㏈
이주(Li-Shu),노재우(Jae-Woo Noh),바양뭉흐 엥흐바야르(Bayanmunkh Enkhbayar),방재훈(Jae-Hoon Bang),안병철(Bierng-Chearl Ahn) 한국정보기술학회 2016 한국정보기술학회논문지 Vol.14 No.8
In this paper, a wideband Bøifot ortho-mode transducer operating at the E-band is designed and fabricated. The proposed ortho-mode transducer consists of a polarization separation section having dual ridges and a T-shaped divider, 6 E-plane bends and an Y-shaped junction. A common port of the ortho-mode transducer is employed with the square waveguide having dimensions of 3.1×3.1mm and its side/straight ports are implemented with the WR-12 rectangular standard waveguide. In designing the ortho-mode transducer, each component is individually optimized and then the overall configuration is assembled. The effects on the major parameters are analyzed with the parametric-sweep methods for the combined structure. The optimally designed ortho-mode transducer is fabricated with 2 split blocks. The fabricated ortho-mode transducer has a reflection coefficient of less than -15dB, a transmission coefficient of less than 0.4dB and an isolation between ports of greater than 32dB over the frequency range 60-95GHz.
이찬희(Chan-Hee Lee),차재호(Jae-Ho Cha),전동하(Dong-Ha Jun),방재훈(Jae-Hoon Bang) 한국정보기술학회 2016 한국정보기술학회논문지 Vol.14 No.4
In this paper, a measuring apparatus for LF-band coil magnetic field strengths is proposed to enhance its productivity. The proposed apparatus consists of a transceiver circuit connected to test and receiving coils, two MCU chips for controlling the transceiver circuits and monitoring measured voltage/current, and an LCD monitor for displaying measured values. The coil calibration constant k is experimentally obtained in order to calculate the magnetic field strengths from the induced voltage on a receiving coil. A current monitoring circuit and a full bridge switching circuit are employed for accurate measurement of the induced voltages on the receiving coil. An experimental method is carried out to verify the performances of the fabricated apparatus. The measured magnetic strength of a test coil shows a error of less than 3.5% between the fabricated apparatus and the experimental method.
아리온밧볼드(Ariun Batbold),오던토이아 바산체렌(Odontuya Baasantseren),방재훈(Jae-Hoon Bang),안병철(Bierng-Chearl Ahn),임태욱(Tae-Wook Lim) 한국정보기술학회 2012 한국정보기술학회논문지 Vol.10 No.2
This paper describes the design of an X-band dielectric resonator oscillator(DRO) based on a pseudomorphic high electron mobility transistor(pHEMT). DRO’s are widely used as a local oscillator for their high stability. In this paper, we realized a DRO employing a pHEMP with high efficiency and stable output, a series-coupled dielectric resonator, input and output matching circuits, a frequency-tuning plate, and a metallic cavity. The transistor’s instability is increased by adding a capacitive impedance at the source of the pHEMT. Starting from the initial design based on the oscillators small signal model, an optimum design of the oscillator is obtained using a CAD tool. The designed oscillator is fabricated and tested. The fabricated oscillator shows a stable oscillation with 1.5-4.5㏈m output at 10.5-10.9㎓.