• 한국전자파학회지:전자파기술
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• 제5권3호
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• pp.48-58
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• 1994

본 논문에서는 EMI/EMC 측정용 안테나로서 다이폴 소자가 료차된 삽자형 대수-주기 다이폴 안테나 (CLPDA: Crossed Log-Periodic Dipole Antenna)를 제시하고 모멘트 법과 전송선로 이론을 결합하여 해석하였다. 이 안테나의 광대역 특성을 고려하여 전 주파수 범위에서 임피던스 정합에 중점을 두었으며, 이에 따라 트윈-붐(Twin-boom) 급전 방식을 사용하였다.해석 결과로써 전류 분포, 입력 어드미턴스, 복사 패턴 및 이득을 계산 하였으며, 실제 CLPDA를 설계하여 복사 패턴과 이득을 측정하였다. 제작한 CLPDA의 측정치는 주어진 주파수 범위(200MHz~500MHz)내에서 이론치에 근접하게 나타났다.

• 한국산학기술학회논문지
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• 제7권2호
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• pp.145-149
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• 2006

본 논문에서는 RFID 태그용 UHF밴드 전방향성 안테나를 설계하였다. 전방향 방사특성과 소형화를 위해서 로딩 다이폴을 교차시키는 방법과 구부리진 다이폴을 교차시키는 방법을 나타내었다. 다이폴 간의 급전 위상차를 90도 되게 급전함으로써 E면 방사패턴이 전방향 특성을 갖도록 하였다. 마일라 재질 위에 칩 입력임피던스와 공액 정합되도록 구현한 3종류 안테나에 대한 반사특성은 -10 dB 기준으로 670-1,050 MHz, 700-1,250 MHz 및 600-1,020 MHz의 광대역 특성을 얻었다. E면 및 H면 모두가 무지향인 전방향 방사특성을 보였다.

• Journal of electromagnetic engineering and science
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• 제13권1호
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• pp.44-50
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• 2013

In this paper, we present a circularly polarized (CP) composite cavity-backed crossed dipole antenna for global positioning system (GPS) applications. We produce the CP radiation by crossing two dipoles through a $90^{\circ}$ phase delay line of a vacant-quarter printed ring, which also has a broadband impedance matching characteristic. Two techniques, insertion of meander lines in the dipole arm and arrowhead-shaped trace at its end, are employed to reduce the sizes of the primary radiation element. The compact radiator is backed by a cavity reflector to achieve a wide CP radiation beamwidth. The proposed antenna exhibits a measured bandwidth of 1.450~1.656 GHz for a voltage standing wave ratio (VSWR) < 2 and 1.555~1.605 GHz for AR < 3-dB. At 1.575 GHz, the antenna has a gain of 7 dBic, a frontto-back ratio of 27 dB, AR of 1.18 dB, and 3-dB AR beamwidths of $130^{\circ}$ and $132^{\circ}$ in the x-z and y-z planes, respectively.

• Journal of electromagnetic engineering and science
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• 제14권3호
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• pp.299-305
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• 2014

A wideband circularly polarized (CP) antenna with a single feed is proposed for use in global navigation satellite systems. Its primary radiation elements are composed of two orthogonal bowtie dipoles, which are equipped with double-printed vacant-quarter rings to allow direct matching of the antenna to a single $50-{\Omega}$ coaxial line and to produce CP radiation. The crossed bowtie dipole is appropriately incorporated with a planar metallic reflector to produce the desired unidirectional radiation pattern as well as to achieve a wideband characteristic in terms of impedance matching and axial ratio (AR) bandwidths. The designed antenna was fabricated and measured. The prototype antenna with an overall 1.2-GHz frequency size of $0.48{\lambda}_o{\times}0.48{\lambda}_o{\times}0.25{\lambda}_o$ produced a measured ${\mid}S_{11}{\mid}$<-10 dB bandwidth of 1.05-1.79 GHz and a measured 3-dB AR bandwidth of 1.12-1.64 GHz. It also showed right-hand CP radiation with a small gain variation (${\pm}0.3dB$) and high radiation efficiency (>93%) over the operational bandwidth.

• Journal of electromagnetic engineering and science
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• 제13권4호
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• pp.224-232
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• 2013

This paper describes composite cavity-backed crossed scythe-shaped dipoles with wide-beam circularly polarized (CP) radiation for use in Global Navigation Satellite Systems. Each branch of the dipole arm contains a meander line, with the end shaped like a scythe to achieve a significant reduction in the size of the radiator. For dual-band operation, each dipole arm is divided into two branches of different lengths. The dipoles are crossed through a $90^{\circ}$ phase delay line of a vacant-quarter printed ring to achieve CP radiation. The crossed dipoles are incorporated with a cavity-backed reflector to make the CP radiation unidirectional and to improve the CP radiation beamwidth. The proposed antennas have broad impedance matching and 3-dB axial ratio bandwidths, as well as right-hand CP radiation with a wide-beamwidth and high front-to-back ratio.

• 한국전자통신학회논문지
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• 제14권3호
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• pp.489-496
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• 2019

본 논문에서는 주파수 2.4 GHz에서 동작하는 초소형 이중 교차 다이폴 안테나를 설계 및 제작하였다. 모바일 기기에 적용할 수 있도록 안테나의 크기를 소형화하기 위해 교차 다이폴을 상부 2개 층에 배치하고 하부에 반사평면과 수평형 정합회로 및 그라운드 평면을 각 층에 배치한 구조에서 안테나와 급전부 및 정합회로는 수직 방향 관통비아홀로 연결하였다. 제작된 안테나의 크기는 $21.61mm{\times}16.88mm{\times}1.27mm$이며, 측정된 반사계수는 -31.5 dB이고, -10 dB 이하 대역폭은 112 MHz 이다. 또한 안테나의 이득은 -4 dBi로 무지향성의 방사 특성을 가지므로 모바일 기기용 안테나로 다양한 분야에 확대 적용될 수 있을 것으로 판단된다.

• 전자공학회논문지A
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• 제29A권4호
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• pp.7-13
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• 1992

Diffraction loss occurs when the propagation path is obstructed by mountains and hills between a base station antenna and a moving vehicle antenna in mobile-radio communication. In this paper an approximate mathematical model using Fresnel-Kirchhoff diffraction theory is considered to predict propogation attenuation by natural obstacles with lateral profiles having general shapes. Field tests are conducted using helical and crossed drooping dipole antenna at 820 MHz. The theoretical analysis used in estimating the effects of hills agrees reasonably with experimental data. The results seem to be useful for estimating the level of received power, the minimum allowable input power, the optimum site of base station and consequently, planning terrestrial microwave links.

• Journal of Electrical Engineering and Technology
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• 제9권4호
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• pp.1360-1364
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• 2014

In this paper, RCS characteristics on defect pattern of crossed dipole slot FSS having a finite size have been analyzed. To analyze RCS, we applied the electric field integral equation analysis which applies BiCGSTab algorithm with iterative method and uses RWG basis function. To verify the validity of this paper, RCS of PEC sphere has been compared to the theoretical results and FSSs with defect patterns are fabricated and measured. As defect patterns in FSS, missing one column, missing some elements, and discontinuity in surfaces are simulated and compared with the measurement results. Resonant frequency shifts in pass band and changes in bandwidth are observed. From the results, precisely predicting and designing frequency characteristics over defect patterns are essential when applying FSS structures such as FSS radomes.

• Journal of electromagnetic engineering and science
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• 제19권2호
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• pp.71-81
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• 2019

This paper presents a design methodology for wideband single-layered microwave absorbers with arbitrary absorption at the design center frequency using reactive Salisbury screens. The bandwidth of the absorber increases when the flatness of the reflection response at the design center frequency is maximized. Based on this observation, closed-form design formulas for wideband absorbers are derived. As they are scalable to any design frequency, wideband reactive screens can be systematically realized using two-dimensional periodic crossed-dipole structures patterned on a resistive sheet. Based on this method, a single-layered absorber with a 90% bandwidth improved to 124% of the design center frequency is presented. For the purpose of physical demonstration, an absorber with a design center frequency of 10 GHz is designed and fabricated using a silver nanowire resistive film with a surface resistance of 30 Ω/square. The measured absorption shows a good agreement with both the calculation and the electromagnetic simulation.

• 전기전자학회논문지
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• 제27권1호
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• pp.71-77
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• 2023

본 논문에서는 실내 무선랜 환경에서 인접한 동작 주파수 스펙트럼을 가진 외부 간섭신호를 차단하기 위해 Wi-Fi 6E 시스템에 적용할 수 있는 이중대역 차단 주파수 선택표면을 설계하였다. 제안한 주파수 선택적 표면 구조는 2.4GHz 대역과 6GHz 대역에서 주파수 차단 특성을 가지며, 변형된 교차 쌍극자 구조와 단위 구조간 서로 맞물린 퍼즐 형태를 통해 구현되었다. 제안한 구조는 입사각과 편파에 대해 안정적인 주파수 응답 특성을 갖도록 설계되었으며, 제작 및 실험으로부터 0°~45°의 입사파에 대해 시뮬레이션에서 얻은 결과와 잘 일치하는 것을 확인하였다.