• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.27 no.5
• /
• pp.463-470
• /
• 2016

In this paper, we introduce a method of scattering centers extraction using the polarimetric data. VIRAF software based on the PO (Physical Optics) and PTD(Physical Theory of Diffraction) were used to calculate the surface scattering and the edge or wedge scattering, respectively. In addition, by using the unitary transformation, 4-channel data based on the linear polarization basis were converted to 2-channel data based on the left/vertical-circular polarization basis, leading to data compression coherently. The scattering mechanism was analyzed in terms of the polarization states and different look angles by using the scattering center of a target extracted by the 2D RELAX algorithm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.29 no.9
• /
• pp.707-721
• /
• 2018

In this paper, a small synthetic aperture radar(SAR) system with 30 cm resolution is proposed, and a RAW data-based Doppler parameter estimation and motion compensation algorithm is described in detail. Acquisition of both PolSAR and InSAR data are enabled because there are two channels each in the transmitter and receiver modules. Automotive-based field work is performed to obtain PolSAR data, and signal processing results are ultimately obtained. A motion compensation algorithm is used to mitigate the residual phase error due to platform oscillation, and improved performance is obtained with the motion compensation algorithm using the automotive field test data.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.25 no.5A
• /
• pp.696-701
• /
• 2000

Electronic Toll Collection (ETC) System makes the telecommunication possible between the Beacon and the On Board Unit(OBU) for automatic toll collection. In this paper, the propagation path of microwave is modelled and the induced voltage of receiving antenna is analyzed numerically according to multi-path fading effect. In our modelling, we consider frequency, weather condition, polarization and antenna radiation pattern. Also, we suggest the diversity technique in order to reduce the fading effect. In the resuts, the fading effect is reduced significantly in case of the vertical polarization at the rain condition. In general the circular polarization is the most desirable in this application. The antenna which has the high directivity, is also desirable. Using the space and frequency diversity technique at the Beacon, the fading effect is reduced effectively. These results are compared with our experimental data.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.19 no.2
• /
• pp.301-307
• /
• 2015

In this paper, we consider wiretap channels in the presence of an eavesdropper assuming spatially correlated MIMO(multiple-input multiple-output) channels, where we analyze a physical layer security performance of orthogonal space-time block code(OSTBC) using one-bit feedback assuming cross polarized antennas at each node. In this paper, we present a method to select a transmit-antenna group for OSTBC using one-bit feedback(O-OSTBC) and compare secrecy outage probabilities of various transmit-antenna grouping methods. Especially, we propose an efficient transmit-antenna grouping method by comparing secrecy outage probabilities of O-OSTBC and conventional OSTBC in highly correlated MIMO channels.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2021.06a
• /
• pp.161-161
• /
• 2021

본 연구에서는 금강 상류의 용담댐 유역(930.0 km²)을 대상으로 Sentinel-1 SAR(Synthetic Aperture Radar) 및 Sentinel-2 MultiSpectral Instrument(MSI) 위성영상을 활용한 토양수분 산출연구를 수행하였다. 연구에 사용된 자료는 10 m 해상도의 Sentinel-1 IW(Interferometric Wide swath) mode GRD(Ground Range Detected) product의 VV(Vertical transmit-Vertical receive) 및 VH(Vertical transmit-Horizontal receive) 편파자료와 Sentinel-2 Level-2A Bottom of Atmosphere(BOA) reflectance 자료를 2019년에 대해 각 6일 및 5일 간격으로 구축하였다. 위성영상의 Image processing은 SNAP(SentiNel Application Platform)을 활용하여 Sentinel-1 영상의 편파 별(VV, VH) 후방산란계수와 Sentinel-2의 적색(Band-4) 및 근적외(Band-8) 영상을 생성하였다. 토양수분 산출 모형은 다중선형회귀모형(Multiple Linear Regression Model)을 활용하였으며, 각 지점에 해당하는 토양 속성별로 모형을 생성하였다. 모형의 입력자료는 Sentinel-1 위성의 편파별 후방산란계수, Sentinel-1 위성에서 산출된 식생지수 RVI(Radar Vegetation Index)와 Sentinel-2 위성에서 산출된 NDVI(Normalized Difference Vegetation Index)를 활용하여 식생의 영향을 반영하고자 하였다. 모의 된 토양수분을 검증하기 위해 6개 지점의 TDR(Time Domain Reflectometry) 기반 실측 토양수분 자료를 수집하고, 상관계수(Correlation Coefficient, R), 평균제곱근오차(Root Mean Square Error, RMSE) 및 IOA(Index of Agreement)를 활용하여 전체 기간 및 계절별로 나누어 검증할 예정이다.

• Journal of the Korea Society of Computer and Information
• /
• v.19 no.4
• /
• pp.71-79
• /
• 2014

This paper investigates wideband dual-polarized microstrip antenna with H-shaped coupling slot. These types of antennas are used to prevent deterioration of transmission quality caused by terminal interference or multipath fading, which usually occur when many terminals are used in limited space such as hot-spot zones. The experimental results show that the impedance bandwidth ($SWR{\leq}2$) of 33.98% and the peak gain of 8.58 dBi (at 2.11 GHz) were obtained by the frequency band under 2.7 GHz. The proposed antenna is designed originally for multiple service bands with simple structure and easily be mass-produced for various commercial applications.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.13 no.1
• /
• pp.53-59
• /
• 2002

In this paper, we present design results for an orthomode transducer(OMT) to be used in multi-band antenna feeds. The OMT is realized in the form of a tapered square waveguide, where 18-20 GHz ports are placed in the taper region normal to the waveguide axis, while 30-45 GHz ports are placed in line with the waveguide axis. The reflection coefficient of each port is designed to be less than 20 dB, while the isolation between ports are greater than 15 dB. Thin septa are placed in side ports to reduce the effect of side ports on the return loss of the in-line port. The commercial software HFSS？ is used to design the whole structure.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.23 no.2
• /
• pp.144-150
• /
• 2012

In this paper, circularly polarization patch array antenna of RSE(Road-side Equipment) base station for DSRC(Dedicated Short Range Communication) of ITS(Intelligent Transport System) is proposed. The antenna of RSE base station for DSRC is designed to operate circularly polarization to receive reflected signal from multiplex path effectively. The proposed antenna consisted of microstrip patch and feed line, the slit is inserted in the proximity of the slot of feed structure to generate circularly polarization. The $2{\times}2$ array structure is designed to satisfying gain that DSRC RSE base station antenna required. Measured impedance bandwidth and axial-ratio bandwidth are satisfied by all DSRC band of 5.795~5.855 GHz. Vertical and horizontal HPBW of the proposed antenna are both about 43 degrees, it showed gain characteristic of about 11.21 dBi.

• Journal of Korea Water Resources Association
• /
• v.53 no.6
• /
• pp.417-425
• /
• 2020

In order to predict and prevent hydrological disasters such as flood, it is necessary to accurately estimate rainfall. In this paper, an areal average rainfall estimation method using multiple elevation observation data of an electromagnetic wave rain gauge is presented. The small electromagnetic rain gauge system is a very small precipitation radar that operates at K-band with dual-polarization technology for very short distance observation. The areal average rainfall estimation method is based on the assumption that the variation in rainfall over the observation range is small because the observation distance and time are very short. The proposed method has been evaluated by comparing with ground instruments such as tipping-bucket rain gauges and a Parsivel. The evaluation results show that the methodology works fairly well for the rainfall events which are shown here.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.51 no.3
• /
• pp.202-209
• /
• 2014

In this paper, we analyzed the effects by multi-stacking superstrates over the circular-polarized patch antenna. The previous works considered a single-layered superstrate or a superstrate with multiple layers, and did not almost consider the axial ratio at the performance analysis. First, the effect of center frequency shift is analyzed by the variation of air-gap height between patch antenna and superstrate. The center frequency is down-shifted at the smaller air-gap height and has almost the same frequency as patch antenna at the air-gap height of $005{\lambda}_0$. Second, the antenna performance is analyzed by multi-stacking superstrates with the air-gap height of $005{\lambda}_0$. As the number of multi-stacked superstrates increase, antenna gain has a linear increase and axial ratio is exponentially deteriorated. In addition, it has also been observed that the antenna performance has the same trend with the number of multi-stacked superstrates as the thickness of superstrate increases. Finally, we confirmed that it is possible to design the CP patch antenna with the scalable gain and less than 3dB axial ratio by stacking the superstrate.