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Miniaturized Circularly-Polarized Antenna Based on Four Meandered Monopoles
Dae-Su Jeong(정대수),Bong-Sup Sin(신봉섭),Li-Jian Zhang(장 리 지앤),Bierng-Chearl Ahn(안병철) 한국정보기술학회 2014 한국정보기술학회논문지 Vol.12 No.12
This paper presents a miniaturized circularly-polarized antenna based on four meandered monopoles. The proposed antenna is a dual-substrate type, where four meandered monopoles printed on the upper substrate are fed by a series feed network on the lower substrate. Two substrates are connected by a metal post enclosed by a teflon cylinder. The antenna miniaturization is realized by highly meandering monopole arms and transmission lines of the feed network with the size reduction of 78%. Short-circuit stubs for impedance matching of meandered monopoles are employed on the lower substrate for structural simplicity. The fabricated antenna has a dimension of 0.11×0.11×0.022 λ0, -1.9dBic gain, 1.4dB axial ratio, and 11.5dB front-to-back ratio at 915MHz.
안광환(Kwang-Hwan An),신봉섭(Bong-Sup Sin),방재훈(Jae-Hoon Bang),안병철(Bierng-Chearl Ahn) 한국정보기술학회 2014 한국정보기술학회논문지 Vol.12 No.1
This paper presents an UHF-band conformal and small discone antenna suitable for communication between an aircraft and a ground station. The proposed antenna consists of a cone, an upper disk, a lower disk, a metallic cavity and a radome. The discone is installed inside a cavity to minimize the effects to structures around the antenna. Electromagnetic absorbing material is applied to the side wall of the cavity to reduce the effects to the cavity side wall. After greatly reducing the height of a conventional discone antenna, the antenna diameter is reduced by placing two disks above the cone. Starting from a prototype structure, the antenna is optimally designed on the basis of parametric analyses. The optimally designed antenna has a diameter of 500mm(0.75 wavelength at the center frequency) and a height of 62.5mm(0.093 wavelength). Measurements of the fabricated antenna show that the proposed antenna has a maximum gain of 0dBi in the elevation direction and .1.2dBi in the azimuth direction, and a reflection coefficient of less than .10dB over 0.43-0.47GHz.
정용선(Yong-Sun Jung),자르갈사이칸 나이암바얄(Jargalsaikhan Nyambayar),신봉섭(Bong-Sup Sin),고형석(Hyung-Suk Koh),안병철(Bierng-Chearl Ahn) 한국정보기술학회 2014 한국정보기술학회논문지 Vol.12 No.8
This paper proposes a near-field RFID reader antenna based on a loop. The proposed antenna consists of a loop loaded with inductors and resistors, a top ground plane for adjusting the far-field gain, a balun and a metal housing. The near magnetic field is generated by a loop consisting of a circular wire and two orthogonal linear wires. Four inductors are placed on the loop to reduce the loop size and four resistors are used to obtain an impedance matching and to control the near magnetic field strength. A ground plan is placed around the loop to reduce the far-field gain of the antenna. A special balun structure is employed to reduce the radiation from the feeding coaxial cable. The loop and the feeding coaxial cable are placed in a metal housing to produce the near magnetic field only in the region just above the antenna. The antenna is optimally designed using a commercial software, then fabricated and tested. The fabricated antenna has a reflection coefficient less than -10dB over 903-921MHz, a far-field gain of -14.5dB, an H-field of 0.38A/m at 40mm above the antenna surface and a tag read distance up to 630mm when a power of 25dBm is supplied to the antenna.
김호진(Ho-Jin Kim),임주영(Ju-Young Lim),신봉섭(Bong-Sup Sin),민재용(Jae-Yong Min),안병철(Bierng-Chearl Ahn) 한국정보기술학회 2014 한국정보기술학회논문지 Vol.12 No.10
This paper proposes a conformal fuze antenna for the transmission of S-band telemetry signals. The proposed antenna consists of rectangular patches conformal to the fuzes cylindrical metal surface and an associated feed circuit. Two patches are placed at 0° and 180° locations on the fuze surface and fed with powers of equal magnitude and 180° phase difference. Each patch is fed by a 100Ω microstrip line where the inset feed structure in employed for impedance matching with the 100Ω line. The antenna is realized on a 0.5mm thick substrate with an integrated feed network and a low-loss dielectric material with a thickness of 2.5mm is placed between the fuze surface and the substrate to increase the bandwidth. Measurements of the fabricated proposed antenna has a bandwidth 43MHz at S-band, a maximum gain of 3.7dBi, a dipole-like radiation pattern with nulls in the fuzes axial direction.