• Title/Summary/Keyword: impedance matching

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Design of Tag Antenna without Shadow Zone in Readable Pattern (인식 음영 구역을 제거한 RFID 태그 안테나 설계)

  • Cho, Chi-Hyun;Choo, Ho-Sung;Park, Ik-Mo
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.16 no.12 s.103
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    • pp.1206-1212
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    • 2005
  • In this paper, we propose a novel antenna structure which uses the electric and magnetic currents so as to eliminate nulls on their radiation pattern. The tag antenna was matched to the conjugate impedance of the commercial tag chip using the modified double T matching network. The radiation efficiency is about $90\%$, and the bandwidth($S_{11}< -10 dB$) is 848${\~}$926 MHz. Also it shows the gain deviation between the maximum and minimum gains about 4 dB at any direction of the tag antenna at the operating frequency. The readable range of the tag is 1.7${\~}$2.4 m for an arbitrary rotation angle of the tag with a commercial tag chip.

An Analysis and Design of Wideband Microstrip Rotman Lens by Contour Integral and Segmentation Method (경계적분법과 세그멘테이션 기법에 의한 광대역 마이크로스트립 로트만 렌즈의 해석 및 설계)

  • 이광일;오승엽
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.14 no.7
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    • pp.769-776
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    • 2003
  • This paper presents analysis and design of microstrip Rotman lens operating over wide band and wide steering angle by the contour integral method along with the segmentation method. All mutual coupling, internal reflections between ports and the discontinuity at every junction are taken into account. Equally spaced ports are designed and realized, which make suppress output ripple through the array ports. Impedance matching and mutual coupling between ports are analyzed and optimized using 12 input and 12 output exponential tapers. The measured results of fabricated lens show ${\pm}$ 1.8 dB insertion loss deviation over 6∼18 GHz wide frequency range and beam steering accuracy less than 1$^{\circ}$over ${\pm}$53$^{\circ}$angle and agrees well with the analysis results.

Design of a Ku-Band Quasi-Yagi Antenna Array Using an Ultra-Wideband Balun (초광대역 발룬을 이용한 Ku 대역 Quasi-Yagi 배열 안테나 설계)

  • Woo, Dong-Sik;Kim, Young-Gon;Cho, Young-Ki;Kim, Kang-Wook
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.19 no.2
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    • pp.207-213
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    • 2008
  • A simplified design procedure for quasi-Yagi antenna arrays using an ultra-wideband balun is presented. The proposed antenna design procedure is based on the simple impedance matching among antenna components: i.e., balun, feed, and antenna This new broadband and high gain antenna array is possible due to the ultra-wideband performance of the balun. As design examples, wideband $1\times4$ and $1\times8$ quasi-Yagi antenna arrays are successfully designed and implemented in Ku-band with frequency bandwidths of about 50 % and antenna gains of 9$\sim$10 dBi and 11$\sim$12 dBi, respectively. And the simulated and measured results demonstrate wide bandwidths and good radiation properties. These antenna arrays can be applied to various phased-array and spatial power combining systems.

High-Efficiency GaN-HEMT Doherty Power Amplifier with Compact Harmonic Control Networks (간단한 구조의 고조파 정합 네트워크를 갖는 GaN-HEMT 고효율 Doherty 전력증폭기)

  • Kim, Yoonjae;Kim, Minseok;Kang, Hyunuk;Cho, Sooho;Bae, Jongseok;Lee, Hwiseob;Yang, Youngoo
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.26 no.9
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    • pp.783-789
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    • 2015
  • This paper presents a Doherty power amplifier(DPA) operating in the 2.6 GHz band for long term evolution(LTE) systems. In order to achieve high efficiency, second and third harmonic impedances are controlled using a compact output matching network. The DPA was implemented using a gallium nitride high electron mobility transistor(GaN-HEMT) that has many advantages, such as high power density and high efficiency. The implemented DPA was measured using an LTE downlink signal with a 10 MHz bandwidth and 6.5 dB PAPR. The implemented DPA exhibited a gain of 13.1 dB, a power-added efficiency(PAE) of 57.6 %, and an ACLR of -25.7 dBc at an average output power of 33.4 dBm.

MIMO Circular Polarization Feed Network for Communication Performance Improvement of Land Mobile Satellite System (육상 이동 위성 시스템의 통신 성능 향상을 위한 MIMO 원형 편파 급전 네트워크)

  • Han, Jung-Hoon;Myung, Noh-Hoon
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.24 no.4
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    • pp.426-435
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    • 2013
  • In this paper, we propose the MIMO circular polarization feed network to enhance the communication performances from the previous $2{\times}2$ MIMO channel to $4{\times}4$ channel for Land Mobile Satellite communication system. The only possibility to extend the communication channel is to use the additional satellite because of the limitation of satellite spaces to install additional antennas. For overcoming this problems, we propose the MIMO circular polarization feed network to secure the isolation characteristics without the distant antenna space. The port isolation characteristics and each port impedance matching conditions are numerically verified and we suggest the $4{\times}4$ MIMO channel model of the proposed system and the performances are verified. The fabricated circular polarization patch antennas with the proposed feed network are measured in the reverberation chamber and 7~10 dB of diversity gain and 80 % increasement of channel capacity are obtained.

A Study on Rectangular-Ring Patch Active Antenna with Dual Polarization Diversity (이중편파 다이버시티 특성을 갖는 사각 링 구조의 능동형 패치 안테나에 관한 연구)

  • Yun, Gi-Ho
    • Journal of IKEEE
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    • v.13 no.3
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    • pp.72-79
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    • 2009
  • This paper describes a compact microstrip active antenna with dual polarization. The antenna, receiving both a left-hand circularly polarized wave and a right-hand circularly polarized wave, has a function of polarization diversity. A square-shaped empty room is located on the inside of the microstrip radiator so that the size has been reduced. And slots are added around feeding point to improve input matching. Also, amplifier and switching circuitry are placed at the empty room to increase antenna gain and to select one of the circular polarizations, respectively. The proposed antenna has been applied to GPS(global positioning system). The measurement results show that it has 10dB-impedance bandwidth, 3dB axial bandwidth of about 50MHz, 3dB beamwidth of 90degree, and gain of 13dBi, respectively, for RHCP. Also, it has 3dB axial bandwidth of about 50MHz, 3dB beamwidth of 84 degree, and gain of 12dBi, respectively, for LHCP.

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A Study on Characteristics of the Twin Tree Array Structure of the Triangular Patch Array Antenna (삼각형 패치 트윈 트리 배열 안테나의 특성 연구)

  • Chang, Tae-Soon;Kang, Sang-Won
    • Journal of IKEEE
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    • v.24 no.2
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    • pp.372-377
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    • 2020
  • This paper is based on the triangular inset patch antenna as the basic structure, and the array structure is the twin tree form to improve the antenna's main lobe gain and reduce the side lobe gain. A twin tree structure was implemented by placing two identical trees of 2-4-6 arrays of triangular inset patches side by side. The parametric analysis confirmed that the gap between tree structures arranged side by side is most effective for impedance matching. The fabricated antenna has a gain of 16.74 dBi at 24.15 GHz, and the beam width of the main lobe is 22° in the E-plane and 6° in the H-plane. The antenna size was 125 mm × 50 mm, and a Taconic TLC substrate with a dielectric constant of 3.2 was used. Although the main lobe gain is improved over the twin tree structure, The directivity in the beam pattern due to the mutual interference of the two tree array structure can be improved.

Design of X/Ku band Waveguide Diplexers with H-plane T-junction (자계면 T-접합 구조를 갖는 X/Ku 밴드 도파관 다이플렉서의 설계)

  • Eum, Jeong-Hee;Choi, Hak-Keun;Song, Choong-Ho
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.13 no.2
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    • pp.33-39
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    • 2013
  • In this paper, X/Ku band waveguide diplexers with H-plane T-junction for satellite communication systems is proposed and its characteristics is cinfirmed. Two frequency bands such as X(7.25 ~ 8.4 GHz) and Ku(12.25 ~ 14.5 GHz) can be separated by the proposed waveguide diplexers. A diplexers is normally including low pass filter, high pass filter and junction waveguide. To simplify the structure of the proposed diplexers, the proposed waveguide diplexers is using impedance matching technique on H-plane of the high pass filter without low pass filter. To use vertical and horizontal polarization, the proposed diplexers with orthomode transducer(OMT) characteristics is also designed. Therefore, it is confirmed that the proposed waveguide diplexers can be used as dual-band and dual-polarization diplexers for satellite communication feed systems.

Ring-Type Rotary Ultrasonic Motor Using Lead-free Ceramics

  • Hong, Chang-Hyo;Han, Hyoung-Su;Lee, Jae-Shin;Wang, Ke;Yao, Fang-Zhou;Li, Jing-Feng;Gwon, Jung-Ho;Quyet, Nguyen Van;Jung, Jin-Kyung;Jo, Wook
    • Journal of Sensor Science and Technology
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    • v.24 no.4
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    • pp.228-231
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    • 2015
  • Ultrasonic motors provide high torques and quick responses compared to their magnetic counterparts; therefore, they are widely used in small-scale applications such as mobile phones, microrobots, and auto-focusing modules in digital cameras. To determine the feasibility of lead-free piezoceramics for ultrasonic motor applications, we fabricated a ring-type piezoceramic with a KNN-based lead-free piezoceramic (referred to as CZ5), intended for use in an auto-focusing module of a digital camera. The vibration of the lead-free stator was observed at 45.1 kHz. It is noteworthy that the fully assembled lead-free ultrasonic motor exhibited a revolution speed of 5-7 rpm, even though impedance matching with neighboring components was not considered. This result suggests that the tested KNN-based piezoceramic has great potential for use in ultrasonic motor applications, requiring minimal modifications to existing lead-based systems.

Design of Rectangular Planar Monopole Antenna with a Double Sleeve (이중 슬리브를 갖는 직사각형 평면 모노폴 안테나 설계)

  • Kang, Sang-Won;Chang, Tae-Soon
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.16 no.1
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    • pp.215-220
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    • 2016
  • In this paper, a wideband antenna accomplished by adding a double sleeve of a rectangular planar monopole structure is proposed. In order to impedance matching of proposed antenna, the antenna performance was improved by adding two gap sleeves and outer sleeve for double sleeve structure. HFSS simulator of ANSYS corp. was used in order to confirm the antenna parameter characteristic. According to the simulation results, the VSWR was less than 2 for the range of 2.5GHz~10.5GHz. The frequency bandwidth is 8GHz. The frequency range of the actual fabricated antenna was 2.92GHz~10.32GHz, the frequency bandwidth is 7.4GHz. The measured radiation pattern frequency is 3GHz, 6GHz and 9GHz. The results are similar with dipole antenna pattern in all frequency. The antenna size is $40{\times}40mm^2$. The utilization possibility of the ultra-wideband planar monopole antenna could be confirmed according to compare and analyze the simulation and measurement data.