• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2002년도 ITC-CSCC -2
• /
• pp.715-718
• /
• 2002

TX/RX dual microstrip 1$\times$8 sub-array antennas are designed, fabricated, and measured for a wideband array antennas in communications. They have a Right Handed Circular Polarization (RHCP) for TX from 7.9 to 8.4 GHz and Left Handed Circular Polarization (LHCP) for RX from 7.25 to 7.75 GHz. Two stacked patches are used for a wideband characteristics and cornertruncated square patches are adopted for a circular polarization. To enhance bandwidth characteristics of a circular polarization, 1$\times$2 sequential rotation arrays are applied. From the measured results, 1$\times$8 microstrip sub-array antennas have a good agreement with those of the simulation. Therefore the sub-array antennas are applicable to satellite communication antennas, active phased array antennas, and radiators in other antennas.

• Journal of Genetic Medicine
• /
• 제10권1호
• /
• pp.52-56
• /
• 2013

Mosaic trisomy 14 syndrome is a well-known but unusual chromosomal abnormality with a distinct and recognizable phenotype. Array comparative genomic hybridization (CGH) analysis has recently become a widely used method for detecting DNA copy number changes, in place of traditional karyotype analysis. However, the array CGH shows a limitation for detecting the low-level mosaicism. Here, we report the detailed clinical and cytogenetic findings of patient with low-frequency mosaic trisomy 14, initially considered normal based on usual cut-off levels of array CGH, but confirmed by G-banding karyotyping. Our patient had global developmental delay, short stature, congenital heart disease, craniofacial dysmorphic features, and dark skin patches over her whole body. Estimated mosaicism proportion was 23.3% by G-banding karyotyping and 18.0% by array CGH.

• Journal of international Conference on Electrical Machines and Systems
• /
• 제2권1호
• /
• pp.1-8
• /
• 2013

Surface permanent magnet-type vernier motors with three magnet array-type rotors (parallel magnetized type, repulsion type, and Halbach type) are compared based on the pull-out torque. It was clarified that increasing the rotor radius increases the pull-out torque at a fixed three-phase alternating voltage. The mechanism for the pull-out torque increase on each magnet array type was different, when the effects of the increase were analyzed based on an induced electromotive force and a synchronous reactance. As a result, the design of the Halbach-type rotor was found to be especially effective for achieving high pull-out torque, because this array type achieves a large induced electromotive force $E_0$ and a small synchronous reactance $x_s$.

• Journal of Positioning, Navigation, and Timing
• /
• 제9권2호
• /
• pp.65-70
• /
• 2020

For a wireless communication system, the angle-of-arrival (AOA) of the signal has a variety of applications. The signal AOA is estimated utilizing various antenna array structure such as Uniform Linear Array (ULA), Uniform Rectangular Array (URA), and Uniform Circular Array (UCA). In this paper, we introduce a cascade AOA estimation algorithm based on the UCA, which is consisted of CAPON and Beamspace MUSIC. CAPON is employed to estimate approximate AOA groups including multiple AOA signals and Beamspace MUSIC is employed to estimate detailed signal AOAs in the estimated AOA groups. In addition, we provide the computer simulation results for verifying and analyzing the performance of the cascade AOA estimator based on UCA.

• Journal of Positioning, Navigation, and Timing
• /
• 제9권2호
• /
• pp.59-63
• /
• 2020

The antenna arrays are known to be effective for GPS anti-jamming and the performance can be improved further if a dual-polarized antenna array is used. However, when the Minimum Variance Distortionless Response (MVDR) beamformer is used as a signal processing algorithm for the dual-polarized antenna array, the anti-jamming performance can degrade in the presence of errors in the steering vector that is a key factor of the MVDR beamformer. Therefore, in this paper, the effect of the steering vector error on the anti-jamming performance of the dual-polarized antenna array is analyzed by simulations and the result is compared to that of the single-polarized antenna array.

• 대한전자공학회논문지
• /
• 제23권6호
• /
• pp.936-943
• /
• 1986

The lasing wavelengths and gain characteristics of the array modes of channel-substrate planar(CSP) lasers are presented. The gain values of array modes are determined from the complex coupling coefficients calculated using the fields of neighborig elements of the array. The computations show that for index guided lasers which have fields that are almost real valued, or have only slight phase curvature, the highest order array mode will have preferred oscillation. The inphase or fundamental mode, which produces only one major lobe in the far-field radiation pattern, will have the lowest modal gain of all array modes. Some of the devices discussed have modal gain differences of less than 10 cm**-1 between the highest and fundamental modes. For optical field confinement factors of about 20%, this gain difference corresponds to avtive layer gains of approximately 50**-1.

• 한국전자파학회:학술대회논문집
• /
• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
• /
• pp.413-417
• /
• 2003

In this paper, a series-fed microstrip array antenna utilized a sub-array with a waveguide slot feeding is presented. This sub-array can reduce the feed loss compared with a full microstrip feed network. The sub-array has been designed both for a broad reflection bandwidth and a flat gain bandwidth from 40.5 GHz to 43.5 GHz. The $24{\times}24$ array antenna has been implemented with the maximum gain of 32.4 dBi.

• 한국전자파학회:학술대회논문집
• /
• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
• /
• pp.501-505
• /
• 2003

There are many antenna array errors. They will distort the array beam pattern and result in an increased sidelobe level. A calibration technique is proposed for correcting the antenna array errors such as mutual coupling and unequal feeder characteristics. These are modeled as a matrix representing the interaction between the radiating elements. The matrix is estimated from the measured array response vectors. The antenna array errors are corrected by modifying the beamforming weight vector. It is verified by the electromagnetic simulation and experiment that the proposed technique reduces the sidelobe level and increases the antenna gain.

• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2001년도 춘계종합학술대회
• /
• pp.191-196
• /
• 2001

본 논문은 광대역 무선통신환경에서 3GCPP(3.4 Generation Partnership proiect)에 기반한 비동기 IMT-2000 시스템의 송수신 시스템을 구성하여 기지국의 수신성능을 분석하였다. 적용된 시스템은 이동국과 기지국간의 Uplink 채널 환경을 고려하였으며, 기지국의 수신신호는 다중경로 페이딩(Multi-path Fading)과 다중접속간섭(Mult Access Interference : MAI)의 영향으로 성능이 열화되며 이에 대한 대책으로 Array 안테나를 채용하였을 경우와 MRC-Diversity(Maximal Combing Diversity)를 채용하였을 경우의 수신성능을 동일한 환경에서 비교 분석하였다. 본 논문에서 적용한 Array 안테나는 수신 신호의 방향에 파라 적응적으로 추적하여 수신 SNR(Singnal-to-Noise power Ratio)을 최대로 형성하여 시스템의 성능을 개선하는 기법이며, 안테나의 방향성(Directivity : =2.67을 이용하는 3-element Array 안테나를 채용하였다. 최대비 합성 다이버시티 기법은 다이버시티 기법 중 수신효율이 가장 좋으며 가지수(L=2)를 함수로 사용하였다. 성능분석 결과 다중경로 페이딩과 다중접속간섭 환경에서 최대비 합성 다이버시티 기법이 Array 안테나보다 약 Eb/No=4[dB]정도 수신효율이 우수하였다.

• 소음진동
• /
• 제10권5호
• /
• pp.886-891
• /
• 2000

In this paper, an iterative array shape estimation technique is presented, which is based on the use of the least squares polynomial fitting to the data from heading sensors. The estimated polynomial shape model is then used for calculating the hydrophone positions on the assumption that the arc distances between sensors are constant. In order to verify the applicability of the proposed algorithm, numerical simulations are performed using two types of non-linear array shapes. In addition the noise effects of heading sensors on the array shape estimation results and the performance of beamformer are also investigated.