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Gangil Byun,Hosung Choo Institute of Electrical and Electronics Engineers 2017 IEEE transactions on antennas and propagation Vol.65 No.9
<P>A method of array manifold calibration using one steering vector measured in a single direction is proposed. The phase information of the measured steering vector is used to derive a novel calibration matrix that is proposed to compensate for the relative phase distortion (RPD) at each antenna port. We also present a metric function defined as a standard deviation of the RPD to determine the optimum calibration angle, which provides intuition for the cause of the accuracy degradation in the direction-of-arrival estimation. To verify the feasibility, a seven-element circular array with identical microstrip patch antennas is fabricated for calibrating its array manifold using a single steering vector measured in a full anechoic chamber. The calibrated array manifold is then used to estimate the direction of arrival, and its accuracy is compared to the calibrated result obtained from the traditional least-squares method. The results demonstrate that the estimation error can be improved by 54.9 degrees compared to the traditional least-squares method, when the number of measured steering vectors is extremely limited.</P>
Gangil Byun,Kyu-Young Hwang,Hyeon-Gyu Park,Sunwoo Kim,Hosung Choo 한국전자파학회JEES 2017 Journal of Electromagnetic Engineering and Science Vol.17 No.2
This study proposes a modeling process of equivalent terrains to reduce the computational load and time of a full- wave electromagnetic (EM) simulation. To verify the suitability of the proposed process, an original terrain model with a size of 3 m × 3 m is equivalently quantized based on the minimum range resolution of a radar, and the radar image of the quantized model is compared with that of the original model. The results confirm that the simulation time can be reduced from 407 hours to 162 hours without a significant distortion of the radar images, and an average estimation error of the quantized model (20.4 mm) is similar to that of the original model (20.3 mm).
Optimum Placement of DF Antenna Elements for Accurate DOA Estimation in a Harsh Platform Environment
Byun, Gangil,Hosung Choo,Hao Ling IEEE 2013 IEEE transactions on antennas and propagation Vol.61 No.9
<P>This paper presents a systematic approach to the optimum placement of direction finding (DF) antennas in a harsh platform environment. A circular array with omni-directional elements is considered for azimuthal direction of arrival (DOA) estimation based on the multiple signal classification (MUSIC) algorithm. The element positions are optimized by the use of a genetic algorithm (GA) in conjunction with the FEKO electromagnetic simulator. The proposed approach is first tested with a generic platform shape. It is then extended to a more realistic military aircraft model with a strong scattering object. The optimized results show a significant performance improvement over the uniform circular array in both platform environments.</P>
Gangil Byun,Hosung Choo,Sunwoo Kim Institute of Electrical and Electronics Engineers 2016 IEEE transactions on antennas and propagation Vol.64 No.4
<P>This communication proposes the design of an arc-shaped antenna array with high isolation to increase the null depth for controlled reception pattern antenna applications. The array is composed of three identical antennas, and each array element is transformed from a rectangular shape to an arc shape to maximize the distance between antenna edges for isolation improvement. The proposed array is fabricated on a 5.5-inch circular substrate to measure antenna characteristics in a full anechoic chamber and is further evaluated by estimating its null depth in conjunction with the conventional power inversion method. The results prove that the array is suitable to effectively improve the isolation and the null depth at low-elevation angles.</P>
Antenna polarisation adjustment for microstrip patch antennas using parasitic elements
Gangil Byun,Hosung Choo IET 2015 Electronics letters Vol.51 No.14
<P>A novel and simple approach to adjust the polarisation properties of a microstrip patch antenna in the entire axial ratio (AR) range is proposed. The proposed antenna consists of a radiating patch and a parasitic strip separated into two parts, and the separated strip is placed at the outer perimeter of the patch for capacitive coupling. This structure enables the antenna to induce opposite-direction currents on the strip, which allows flexible polarisation adjustment by moving the separated positions of the strip. For evaluation, two antennas with linear and circular polarisations are fabricated, and their performance is measured in a full anechoic chamber. The results prove that the proposed approach is suitable for flexible AR adjustment without a significant degradation of the matching characteristics and the design complexity.</P>
Design of Aircraft On-Glass Antennas Using a Coupled Feed Structure
Gangil Byun,Chulhun Seo,Byung-Jun Jang,Hosung Choo IEEE 2012 IEEE transactions on antennas and propagation Vol.60 No.4
<P>This communication proposes a glass-integrated antenna using a coupled feed structure for military FM radio communications on aircraft. The proposed antenna consists of a feed strip and two radiators, printed on the left-side window of the cockpit. The proposed antenna structure is optimized with the genetic algorithm in conjunction with the FEKO EM simulator. The optimized antenna is built and installed on a 1/10-sized KUH-Surion mock-up and antenna performance, such as reflection coefficient and bore-sight gain, is measured in a semi-anechoic chamber. The optimized antenna shows a half-power matching bandwidth of 28% at the center frequency of the military FM radio band and an average bore-sight gain of about -2.60 dBi. The results show that the proposed antenna is suitable for use as a military FM antenna for aircraft applications.</P>
변강일(Gangil Byun),한원근(Wone Keun Han),추호성(Hosung Choo) 한국전자파학회 2011 한국전자파학회논문지 Vol.22 No.2
본 논문에서는 커플링 급전 구조를 가지는 항공기용 양면 인쇄형 글래스 안테나를 제안하였다. 제안된 안테나는 한 개의 급전 선로와 다중 루프 형상의 방사 소자로 구성되며, 조종석 좌측 창문의 서로 다른 면에 위치하여 제한된 면적을 효율적으로 사용하도록 하였다. 제안된 안테나는 유전자 알고리즘을 이용하여 최적화 하였으며, 최적화된 안테나를 1/10 크기의 KUH-Surion에 장착하여 안테나 성능을 측정하였다. 최적화된 안테나는 해당 대역의 중심 주파수에서 33 %의 반전력 대역폭을 가지며, 평균 ?3.49 ㏈i의 전면 방향 복사 이득을 갖는다. 제안된 글래스 안테나의 수신 성능을 평가하기 위해 반경 200 ㎞에서의 수신 전력을 시뮬레이션 하였으며, 그 결과 현재 항공기용 FM 안테나로 사용 중인 pole 안테나와 비슷한 ?60 ㏈m의 최소 수신 전력을 유지하는 것을 확인하였다. In this paper, we propose a double-faced window printed antenna for aircraft applications. The proposed antenna structure consists of a feeding line and a multi-loop radiator located on different sides of the window to use the limited given-area effectively. The proposed antenna is optimized by the genetic algorithm in conjunction with the FEKO EM simulator. The optimized antenna is built and installed on a 1/10 sized KUH-Surion mock-up and antenna performances such as the reflection coefficient and the radiation patterns are measured. The optimized antenna shows a half power matching bandwidth of about 33 % at 60 ㎒ and an average bore-sight gain of about ?3.49 ㏈i. To verify the reception capability of the optimized antenna, we simulated the received power according to a flight scenario. The result confirms that the optimized antenna shows a minimum received power level above ?60 ㏈m at a range of 200 ㎞, which is similar to the pole antenna that is currently used as a FM voice antenna for KUH-Surion.
Design of Small CRPA Arrays with Circular Microstrip Loops for Electromagnetically Coupled Feed
Jun Hur,Gangil Byun,Hosung Choo 한국전자파학회JEES 2018 Journal of Electromagnetic Engineering and Science Vol.18 No.2
This paper proposes a design of small controlled reception pattern antenna (CRPA) arrays using circular microstrip loops with frequencyinsensitive characteristics. The proposed array consists of seven identical upper and lower circular loops that are electromagnetically coupled, which results in a frequency-insensitive behavior. To demonstrate the feasibility of the proposed feeding mechanism, the proposed array is fabricated, and its antenna characteristics are measured in a full-anechoic chamber. The operating principle of the proposed feeding mechanism is then interpreted using an equivalent circuit model, and the effectiveness of the circular loop shape is demonstrated by calculating near electromagnetic fields in proximity to the radiator. The results confirm that the proposed feeding mechanism is suitable to have frequency-insensitive behavior and induces strong electric and magnetic field strengths for higher radiation gain in extremely small antenna arrays.