• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.7B
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• pp.895-900
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• 2001

본 논문에서는 하나의 급전선을 갖는 원형 섹터 마이크로스트립 안테나를 사용하여 서로 수직한 편파 특성을 갖는 이중주파수 안테나를 설계하였다. 여기되는 모드 및 주파수를 공진기 모델을 사용하여 계산하였으며, 반경과 섹터 각도를 파라미터로 하여 여기되는 두 주파수를 설계할 수 있었다. 약 2GHz 대역에서 동작하는 안테나를 제작하여 안테나의 특성을 측정하였다. 안테나의 반경을 고정하고 섹터 각도를 75$^{\circ}$에서 120$^{\circ}$까지 변화시켜, 여기되는 두 주파수의 비가 1.08에서 1.518까지 변하는 것을 볼 수 있었다.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.443-446
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• 2002

In this paper, we present a new design method for a square iris polarizer to be used in dual-band (Ka-band; 20.8 ~21.2 ㎓, 30.6~31 ㎓) antenna feeds. Principles of operation of a square iris polarizer, its design concepts and methods are proposed. Based on proposed methods, a Ka- band polarizer with -35 dB return loss and 0.3 dB axial ratio is designed using the commercial software HFSS.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.7
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• pp.709-715
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• 2002

In this paper, a novel low profile dual feeding microstrip antennas with microstrip and H-shaped aperture feeding are proposed to achieve high isolation and easy feeding, and the validity of the proposed antennas is demonstrated experimentally. In the proposed single and 1$\times$4 array antenna, the measured isolations are less than -49 dB and -48 dB, impedance bandwidths are 4 % at 12.5 GHz and 2.1 % at 14.25 GHz for the VSWR<1.5 in both antennas and maximum gains are 8.25 dBi and 14.2 dBi.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.4
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• pp.515-525
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• 1998

In this paper, for both transmission and reception with single antenna system of satellite communication, dual-frequency antennas which operate simultaneously at 12.5 GHz and at 14.25 GHz are designed, constructed and measured. Also by using dual feeding structure, the problems of single-fed dual-frequency antenna such as the separation of transmitting and receiving signals and single polarization, are solved. Microstrip patch as a radiation element of dual-fed dual-frequency antenna has width and length which are the resonance lengths of the corresponding frequencies for transmission and reception, respectively. The effects of the feed line on the other frequency feeding are minimized with the optimal matching scheme for the feed lines. For solving the space problems of dual-fed two-dimensional array antennas, microstrip-line and coaxial probe feedings are used for each frequency and a two-dimensional $2\times2$ array antenna was designed and measured their characteristics. The experimental results show that errors of resonance frequencies are less than 1.44%, the return losses are less than -21 dB and the isolations between two feeding ports are less than -21 dB. The characteristics of radiation patterns of dual frequency microstrip antenna are measured and evaluated. The directivities, sidelobe levels and cross polarizations are also measured and compared with the simulations. The results show some errors due to the misalignment of coaxial probe feeding.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.3A
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• pp.435-442
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• 2000

In this paper, we analyzed RF-DC conversion efficiency for the dual -polarization rectenna and the antenna position changing. Dual-Polarization rectenna consist of a two major parts, receiving antenna and rectifying circuits. We made dual-polarization 2.45GHz rectenna using the two dipole antennas and patch antenna. Rectifying circuit is consisted by a Schottky-Barrier diode with a large forward current and reverse breakdown voltage. The results of RF-DC conversion efficiency for the each of designed dual-polarization rectenna has 69.1% with 360$\Omega$(dipole type) and 75.4% with 340$\Omega$(patch type ) optimum load resistor. When the each of dual-polarization rectenna has optimal load resistor, it's conversion efficiency shows of $\pm$20% in dipole type and $\pm$5 in patch type at 0~180。position.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4B
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• pp.372-378
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• 2002

In this paper, a narrow-band waveguide channel fitter has been designed and realized for Ku band satellite transponder. Group-delay and amplitude variations of the channel filter have been minimized using a 2-pole reflection type equalizer. The channel filter has been designed to have the 8-pole elliptic response for high frequency selectivity. Dual-mode technique has been adopted for reducing mass and volume of the channel filter and equalizer. The channel filter and equalizer have shown good performance for satellite transponder.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.231-234
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• 2005

In this paper, Dual-polarized Tx/Rx antenna for RFID reader is designed and fabricated to apply to RFID reader. Each feeding network of Tx/Rx is designed to improve the port-isolation and cross-polarization, and sequential rotation feeding scheme has been applied to increase of axial ratio bandwidth. Measured results show that 2.35dBi of antenna gain in 900MHz$\sim$928MHz, 150MHz of 3dB axial ratio bandwidth, -38dB$\sim$-40dB of port-isolation, and -30dB$\sim$-40dB of cross-polarization.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.473-477
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• 2003

In this paper, a integrated structure of a two-element microstrip patch antenna with two feeds for GPS/PCS dual-band operation is proposed. The radiating element for PCS operation is a novel broad band low-profile cylindrical monopole top-loaded with a shorted meander patch, which gives linearly polarized conical radiation pattern and size reduction of patch due to meander line. The radiating element for GPS operation is a novel square-ring microstrip patch with truncated corners and slits. which provide circularly polarized broadside radiation patterns and size reduction due to slots. using dielectric substrate in GPS antenna of proposed antenna provide to improve isolation between two feeds and reduce size of patch. The proposed antenna achieves the bandwidth and polarization requirements of GPS and PCS systems.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.418-422
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• 2003

In this paper a dual-band circularly polarized stacked microstrip antenna for Global Positioning System (GPS) service and Digital Multimedia Broadcasting (DMB) service is designed. By stacking two different corner-truncated square microstrip patches, dual-band, dual polarization characteristic is obtained. Experimental results show impedance bandwidth of 60 MHz (3.8%) and axial ratio bandwidth of 6 MHz (0.4%) in GPS and impedance bandwidth of 126 MHz (4.7%) and axial ratio bandwidth of 30MHz (1.1%) in DMB.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.3
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• pp.138-145
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• 2008

In this paper, the waveguide slot array antenna which is capable of wide beam steering and dual polarization is designed for an X band synthetic aperture radar. In order to improve the restriction of beam steering range and to remove the butterfly lobes, a typical waveguide slot array antenna has been modified. To implement dual polarization, rod excited waveguide slot elements and ridge waveguide slot elements are alternately arranged. Location of slots, inclination of rod and offset distance of slots are determined on using array characteristic and conductance constant with radiating power on slots. The designed antenna is manufactured and measured with Near-filed measurement method.