• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.5 no.2
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• pp.20-28
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• 1994

Theoretical radiation patterns for the corrugated horn antenna are analyzed by vector integral method and quasi-optics. The formular of the radiated fields for the corrugated horn antenna can be obtained by the potentials derived the equivalent current sources from hybrid fields at horn aperture and also calculated by the expanded mode set of Gaussian - Laguerre based on the quasi - optics. From comparison of the radiation patterns between two methods for a corrugated horn antenna designed on 85-115 GHz frequency range, the results are coincided well at center frequency but have some errors at each side frequencies 85 and 115 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.1
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• pp.106-113
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• 2011

In this paper, the non-resonant SWG(Slotted Waveguide) antenna with double slots in narrow wall of rectangular waveguide is designed. Because energy radiated from each slot depends upon inclination angle of slot of the designed antenna, inclination angle of each slot is controlled to satisfy the amplitude distribution for required sidelobe level. Instead of the conventional extraction method of slot conductance, this amplitude distribution is made by the proposed method, which employs far-field radiation pattern calculated by Fourier transform of aperture field distribution on slot. The non-resonant double SWG antenna is designed by the proposed method and is manufactured. The antenna performances are measured and compared with the simulated results.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.7
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• pp.81-89
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• 2017

Autofocus(AF) Method is essential to overcome the performance degradation due to motion measurement errors under airborne SAR environment. In this paper, back-projection algorithm(BPA) is applied to SAR raw data acquired under the squinted mode, and preprocessing algorithm of AF for BPA is investigated. To apply AF to SAR image effectively, image backplane rotation method and doppler location alignment function for BPA are proposed. The proposed method is applied to SAR raw data acquired in a flight test and shows excellent performance improvement in real data.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.8
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• pp.826-831
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• 2008

This paper presents hybrid antenna(HA) design based on shaped reflector for mobile satellite communication. HA is composed of a shaped reflector and a feeder having $1{\times}8$ linear phased array, and reflector shaping method is applied for the performance optimization with minimum aperture size. And, in the feeder design, HA has another merit to minimize the manufacturing cost by optimizing the number of element. Proposed HA is designed at Ka-band and can electrically control a beam pattern within ${\pm}3^{\circ}$ in the basic angle of $+45^{\circ}$ in elevation. This antenna is designed to meet ITU-R S.465-5 for beam pattern including side-lobe level.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.1
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• pp.115-121
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• 2012

In this paper, the design and fabrication of slot array in the broad wall of the waveguide for Ka-band monopulse radar are discussed. The aperture distributions are designed for the desired antenna gain, beamwidth and Side-lobe Level(SLL), and then slot parameters, such as lengths and offsets, are obtained for corresponding to each slot admittance in the equivalent circuit by using Elliot's array synthesis procedure. MWS-CST simulation shows the return loss below -10 dB, antenna gain above 32 dBi, 3 dB beamwidth of 3.7 degree and SLL of -20 dB. In order to demonstrate the expected results, the designed antenna is fabricated and measured.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.4
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• pp.655-662
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• 2011

SAR(Synthetic Aperture Radar) has the ability to generate high resolution images regardless of a weather condition(e.g. visibility good or poor and day or night, etc.). SAR is considered as one of the most important powers and needs for the future since it has been utilized in a number of important military fields such as early warning, urban defense, missile guidance system, etc. Additionally there are many civilian demands and applications in aviation, traffic control, earth and space explorations, weather forecast etc. This days, the ability to acquire and analyze information is needed to cope with the urgency of global politics and international changes. In this paper, technical survey and development review for SAR systems are investigated to derive the core and immature technologies of domestic defense industry.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.2
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• pp.207-217
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• 1999

When the feed of an offset reflector antenna is displaced from the focal point, the phase distortion results in the aperture field distribution, which in turn gives rise to a deviation of maximum beam, a decrease in gain, and an increase in sidelobes. In order to study these scan characteristics, an offset reflector antenna with the defocused feed is analyzed by a series expansion method using the Zernike polynomials, which can be used to calculate radiation pattern fast and exactly. And from the analyzed results, scan loss data in terms of reflector geometry are presented. And also, the BDF (beam deviation factor) expression is derived with offset reflector configuration analytically, and calculated results and simple formula of BDF are presented for determining beam deviation characteristics.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.6
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• pp.636-636
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• 1997

This paper presents the design and fabrication of a shaped-beam array antenna which will be used for a PCS basestation using structure that is coupled to a microstrip line by an aperture on the intervening ground plane. The shaped-beam pattern is obtained by an antenna synthesis method. An array antenna considering the mutual coupling between array elements(patches) and a feeding network are designed by CAD tools. The feeding network is designed by using the Wilkinson power divider to obtain the optimized shaped-beam. The designed results are compared with the measured data.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.3
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• pp.425-431
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• 2001

In this paper, on aperture-coupled microstrip cylindrical dielectric resonant antenna(DRA) consisting of dielectric material with permittivity ${\epsilon}_{r}$ = 36 is designed and fabricated fir wireless LAN. First of all, the feedline length, width, slot length and width of the feeding element were calculated using the theory of microstrip transmission line. Radiation element is designed using the theory of cylindrical dielectric cavity, Resonant frequency of the fabricated cylindrical DRA is 2.449 GHz and VSWR, return loss and bandwidth is 1.009, -47 dB and 70 MHz, respectively. Front-to-back radiation ratio is about 12 dB and 3 dB beamwidth of E-plane and H-plane is 110$^{\circ}$ and 90$^{\circ}$ , respectively.

• Journal of the Korea Institute of Military Science and Technology
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• v.23 no.4
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• pp.328-336
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• 2020

This paper presents an asymptotic analysis method using the PO(physical optics) approximation technique to analyze the scattering contribution of an electrically large object partially coated with a radar absorbing material(RAM). By using the feature of the PO technique that can calculate the equivalent current value for each mesh independently, instead of analyzing the entire structure, scattering analysis was performed only by calculating the current on the area where the RAM coating is applied. By the numerical examples, the accuracy and the computation time of the proposed method were verified, and the computational efficiency of inverse synthetic aperture radar(ISAR) of the electrically large objects that require enormous resources is improved.