• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1664-1667
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• 2003

Aperture-coupled microstrip antenna is one type of microstrip antennas. This type of antenna has bandwidth wider than simple microstrip antenna. Herein, we use two substrates, that have the same dielectric constant 2.47 (PTFE-quartz) in which upper substrate is a rectangular patch. The microstrip patch is fed by a microstrip line which is printed on lower substrate, through an aperture or slot in the common ground plane of patch and microstrip feed. This antenna is analyzed by using Finite Difference Time Domain (FDTD) method the specific design frequency 10 GHz and match impedance is 50 ohms. The simulation results of its characteristics are input impedance, return loss, VSWR and radiation patterns respectively.

• Journal of Korea Society of Industrial Information Systems
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• v.6 no.4
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• pp.6-11
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• 2001

In this paper, the aperture-coupled U-slot microstrip patch antenna is studied for the bandwidth improvement. The aperture is used as a mechanism for coupling the radiating element to the microstrip feedline, and the aperture-coupled configuration provides the advantage of isolating spurious feed radiation by the use of common ground plane. Experimental results such as return loss, VSWR, radiation pattern and gain measurements are presented on the aperture-coupled U-slot microstrip patch antenna. The impedance bandwidth (VSWR≤2) of the antenna is 6.4% centered at 2.35GHz, and the average gain is 5.3 dBi.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1058-1060
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• 2003

A ground control point (GCP) is a point on the surface of Earth where image coord inates and map coordinates can be identified. The GCP is useful for the geometric correction of systematic and unsystematic errors usually contained in a remotely sensed data. Especially in case of synthetic aperture radar (SAR) data, it has serious geometric distortions caused by inherent side looking geometry. In addition, SAR images are usually severely corrupted by speckle noises so that it is difficult to identify ground control points. We developed a ground point extraction algorithm that has an improved capability. An application of radargrammetry to Daejon area in Korea was studied to acquire the geometric information. For the ground control point extraction algorithm, an ERS SAR data with precise Delft orbit information and rough digital elevation model (DEM) were used. We analyze the accuracy of the results from our algorithm by using digital map and GPS survey data.

• Proceedings of the KIEE Conference
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• 2001.11c
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• pp.30-33
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• 2001

This paper discusses the system design of a synthetic aperture radar system based on a pulse-echo radar. The design consists of an ultra-wide bandwidth antenna, an amplitude modulation, timing stabilities, and high speed a/d conversions with an equivalent-time sampling. Experiment results show that GPR(Ground Penetrating Radar) can be used to explore buried electric facilities.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.6
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• pp.459-469
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• 2017

An air-to-ground guidance missile aimed to hit a main battle tank(MBT) should detect a ground moving target and estimate the target position to guide. In this paper, we detect a front ground moving target by using FMCW(Frequency Modulated Continuous Wave) and estimate the position by forward-looking SAR(Synthetic Aperture Radar) via scanning certain front ground section by steering a beam with narrow beamwidth left to right mechanically. Also, by MLE(Maximum Likelihood Estimation), degree of how fast the target approach or recede from the radar can be figured out from the estimated radial velocity of the moving target. Subsequently, we generate a radar image via corrected matched filter from phase history including the radial velocity.

• Journal of the Korea Institute of Military Science and Technology
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• v.25 no.1
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• pp.30-44
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• 2022

The advent of deep learning-based algorithms has facilitated researches on target detection from synthetic aperture radar(SAR) imagery. While most of them concentrate on detection tasks for ships with open SAR ship datasets and for aircraft from SAR scenes of airports, there is relatively scarce researches on the detection of SAR ground vehicle targets where several adverse factors such as high false alarm rates, low signal-to-clutter ratios, and multiple targets in close proximity are predicted to degrade the performances. In this paper, a dataset of ground vehicle targets acquired from TerraSAR-X(TSX) satellite SAR images is presented. Then, both detection and instance segmentation are simultaneously carried out on this dataset based on the deep learning-based Mask R-CNN. Finally, this paper shows the future research directions to further improve the performances of detecting the SAR ground vehicle targets.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.9
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• pp.851-857
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• 2002

A two-arm microstrip spiral antenna with a circular aperture on the ground plane that generates a circularly polarized conical beam is presented in this paper. We obtained circularly polarized conical beam by using two spirals that are excited in-phase from the microstrip feed lines. The main beam directions of the conical beam from the broadside are approximately 40$^{\circ}$ in the range from 5 GHz to 6.5 GHz, and 58$^{\circ}$ from 9 GHz to 11 GHz. Since the proposed antenna has omni-directional conical beam pattern, it is suitable for use in mobile communication systems.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.11
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• pp.1063-1069
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• 2011

NCTR(Non-Cooperative Target Recognition) and ATR(Automatic Target Recognition) are methodologies to identify military targets using radar, optical, and infrared images. Among them, a strategy to recognize ground targets using synthetic aperature radar(SAR) images is called SAR ATR. In general, SAR ATR consists of three sequential stages: detection, discrimination and classification. In this paper, a modification of the polar mapping classifier(PMC) to identify inverse SAR(ISAR) images has been made in order to apply it to SAR ATR. In addition, a preprocessing scheme can mitigate the effect from the clutter, and information on the shadow is employed to improve the classification accuracy.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.8
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• pp.781-787
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• 2004

In this paper, a novel dual and wide band aperture stacked patch antenna for Cellular/PCS/IMT-2000 base station is presented. It consists of single microstrip patch having notches along the radiating patch, two dielectric substrates and a form material. To achieve wide band characteristic, we utilize the coupling effect between the notched patch and the resonant aperture in the ground plane and by properly cutting notches on the patch, an aperture stacked patch antenna could be designed to yield dual frequency operation. By the proper choice of resonant aperture size and height of a foam material, dual and wide band characteristic could be realized the measured impedance bandwidth(1:1.5 VSWR) of designed antenna at lower band(860 MHz) reaches 77 MHz and covers the Cellular CDMA band(824∼894 MHz). The measured impedance bandwidth(1:1.5 VSMR) of the designed antenna at upper band(1,960 MHz) is about 550 MHz and covers both the PCS band(1,750∼l,870 MHz) and the for-2000 band(1,920∼2,170 MHz). Good broadside radiation with high gain(5.65∼7.4 dBi) characteristics have also been observed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.9
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• pp.1056-1064
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• 2010

This paper presents the approximate analysis method for the symmetric transmission line crossing the aperture in an backplane. The method of moments is used to determine the aperture impedance for the construction of the equivalent transmission line that the aperture impedance apply to the transmission line as the shunt impedance. As the results, the insertion loss increases at the specific frequency range for the impedance matching. In the case of the mismatching, we are confirmed to the insertion gain at the specific frequency. Also the horizontal length of the aperture affects to the transmission line better than vertical length. The measurement of the insertion loss is performed to verify the theoretical analysis.