• Journal of electromagnetic engineering and science
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• v.18 no.2
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• pp.117-128
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• 2018

In this paper, compact linear dual polarized series-fed $1{\times}2$ linear and $2{\times}2$ planar arrays antennas for airborne SAR applications are proposed. The proposed antenna design consists of a square radiating patch that is placed on top of the substrate, a quarter wave transformer and $50-{\Omega}$ matched transformer. Matching between a radiating patch and the $50-{\Omega}$ microstrip line is accomplished through a direct coupled-feed technique with the help of an impedance inverter (${\lambda}/4$ impedance transformer) placed at both horizontal and vertical planes, in the case of the $2{\times}2$ planar array. The overall size for the prototype-1 and prototype-2 fabricated antennas are $1.9305{\times}0.9652{\times}0.05106{{\lambda}_0}^3$ and $1.9305{\times}1.9305{\times}0.05106{{\lambda}_0}^3$, respectively. The fabricated structure has been tested, and the experimental results are similar to the simulated ones. The CST MWS simulated and vector network analyzer measured reflection coefficient ($S_{11}$) results were compared, and they indicate that the proposed antenna prototype-1 yields the impedance bandwidth >140 MHz (9.56-9.72 GHz) defined by $S_{11}$<-10 dB with 1.43%, and $S_{21}$<-25 dB in the case of prototype-2 (9.58-9.74 GHz, $S_{11}$< -10 dB) >140 MHz for all the individual ports. The surface currents and the E- and H-field distributions were studied for a better understanding of the polarization mechanism. The measured results of the proposed dual polarized antenna were in accordance with the simulated analysis and showed good performance of the S-parameters and radiation patterns (co-pol and cross-pol), gain, efficiency, front-to-back ratio, half-power beam width) at the resonant frequency. With these features and its compact size, the proposed antenna will be suitable for X-band airborne synthetic aperture radar applications.

• ETRI Journal
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• v.26 no.3
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• pp.262-264
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• 2004

We investigate the characteristics of a wideband and high-gain cavity-backed slot antenna in terms of the reflection coefficients, radiation patterns, and gain. A cavity-backed slot antenna structure includes baffles, reflectors, and thick ground planes. The measured gain and bandwidth of a 10-dB return loss in a cavity-backed $2{\times}2$ array slot antenna with $h_1=2 $mm, d=2 mm are 15.5 dBi and nearly 27%, respectively, at 42 GHz. Baffles and reflectors are used to increase antenna gain, thus reducing the coupling among the slots on the thick ground plane.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.389-393
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• 2000

마이크로스트립 안테나는 다양한 장점에 의해 배열 안테나로서 각광을 받고 있다. 하지만 표면 전파에 의한 음영각 발생 및 이에 따른 조향각이 제한된다는 단점을 가지고 있다. 본 논문은 이러한 문제점들을 해결하기 위하여 radome이 올려진 cavity-backed 단일 방사 소자들을 showed array 구조론 통해 해결하는데 초점을 두었으며, 알고리즘에 대한 설명과 본 구조를 이용하여 실제 성능의 개선을 가져 올 수 있음을 보이고자 한다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.2
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• pp.105-116
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• 1996

The design and analysis of the transversely fed EMC(electromagnetically coupled) microstrip dipole have been accomplished by using the integral equation and MOM(method of moment)in frequency domain in order to find the current distribution of the dipole. In this study, we proposed the possibilities for design and analysis of EMC micro-strip dipole array antenna by means of calculating the current distribution of each dipole directly using the FDTD(finite difference time domain) method. In this case, we applied the formulation which is the finite difference expression of the Maxwell's integral equation. From the current distribution of each dipole, we calculated the far field electric component and showed that the calculation process and running time was reduced with respect to the method which calculates the radiation field with surface electric and magnetic current density.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.2
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• pp.39-46
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• 1990

In this paper, Rectangular microstrip patch array antenna. relative current of which is distributed to 1:2:2:1, is designed and fabricated by using Tschebyscheff's polynominal expression and is verified by theoretical analysis and experiment. Seeking for more accurate resonant frequency, an equivlent network, which is consisted including feed line and power distribution line, is analyzed by using the analysis method of transmission line mode. As a result of their comparison and examination, such as resonant frequency by fringing effects, by return loss, by experiment, it is conformed that errors are not barely and agreed with each other. is also agreed with a measured values.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.1
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• pp.73-82
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• 1997

This paper discusses the design and implementation of parabola, lens, and $32{\times}8$ rectangular microstrip patch array antennas at 77GHz for vehicular radar applications. The parabola size was $7{\times}10$ cm and the f/D was 0.263. Open waveguide(WR-12) was utilized as the feed antenna. Two types of lens antennas with f/D=0.5 were investigated ; one was a plano-convex and the other was a double-convex. A patch array antenna was designed using a transmission line model and experimented. Comparing the theoretical values with the measured ones for four antennas, the results were agreed well in 3 dB BW and radiation patterns, while the gain of the patch array antenna was degraded as much as -25 dB due to the feed network and microstrip-to-coax-to-waveguide transition losses.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.4
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• pp.209-215
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• 2002

This paper describes beam-tilting characteristics of horizontally polarized EMCD (electromagnetically coupled dipole) array antennas. The result of one element radiator is used for array elements designs and is evaluated its characteristics. Theoretical frequency characteristics and radiation pattern of the horizontally polarized EMCD array antennas analyzed by FDTD method agree well with the measured results of the practically fabricated way antennas. The measured main beam tilt ang1e and 3 dB beam width of the fabricated 20-element array antennas are 47$^{\circ}$and about $\pm$7.5$^{\circ}$, respectively. A good radiation pattern and beam tilting characteristics are observed in experiments.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.9
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• pp.896-905
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• 2004

In this paper, the design, fabrication and experiment on a planar array antenna with a flat-topped radiation pattern for a mobile base station antenna were described. The current distribution of an antenna aperture, which is easily realizable in a feeding network compared with the conventional one of sin(x)/x was optimized for shaping a desired flat-topped radiation pattern. The planar array antenna designed in this paper has a rectangular lattice and is composed of array elements of 16${\times}$8. Each radiating element, which is a microstrip element fed coaxially, has a linear vertical polarization and the feed network which use a Wilkinson power divider and a 180$^{\circ}$ ring hybrid coupler as a base element is designed. The flat-topped radiation pattern with 90$^{\circ}$ is shaped by 16 array elements with the element spacing of 0.55 λ$_{ο}$ in the azimuth plane, and the normal radiation pattern with 10$^{\circ}$ is shaped by 8 array elements with the element spacing of 0.65 λ$_{ο}$ in the elevation plane. Also, the planar array antenna is symmetrically divided into four parts. It consists of one hundred-twenty-eight radiating elements, thirty-two 1-4 column dividers, low 1-8 row dividers and one 1-4 input power divider. In order to verify electrical performances of the planar way antenna proposed in this paper, the experimental breadboard operated in tile band of 1.92～2.17 GHz(IMT2000 band) was fabricated, and its experimental results were a good agreement with simulation ones.

• Journal of electromagnetic engineering and science
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• v.14 no.3
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• pp.306-313
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• 2014

A Fabry-Perot resonator cavity antenna for Ku-band application is presented in this paper. The Fabry-Perot cavity is formed by a ground plane and a frequency selective surface (FSS) made of a circular hole array. The cavity resonance is excited by a single-feed microstrip patch located inside the cavity. The measured results show that the proposed antenna has an impedance bandwidth of approximately 13% ($VSWR{\leq}2$) and a 3-dB gain bandwidth of approximately 7%. The antenna produces a maximum gain of 18.5 dBi and good radiation patterns over the entire 3-dB gain bandwidth. The antenna's very thin profile, high directivity, and single excitation feed make it promising for use in wireless and satellite communication applications in a Ku-band frequency.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.371-374
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• 2005

This paper presents the design and fabrication of a cost effective and broad band 8$\times$8 stacked patch array antenna which are backed by a metal cavity operating at 400Hz based on 4 layers LTCC technology. Gain of antenna can be enhanced by using a metal cavity, which can be easily implemented by using LTCC substrates and vias. The broadband performance can be obtained by varying the dimension of patch and the number of layers. Furthermore, to keep the feeding network as smal1 as possible and reduce radiation from feeding network a mirrored patch orientation and embedded micro strip line are adopted, The fabricated antenna is $40\times45\times0.4$ $mm^3$in size. It shows gain 20.4dBi, beam width 10.7deg and impedance bandwidth of l0dE return loss 3.35GHz (40.9$\sim$44.25 GHz), which is about 8% of a center frequency.