• Title/Summary/Keyword: Choke Antenna

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Slotted Waveguide Array Antenna using Dumbbell Patch for Millimeter-Wave (Dumbbell 패치를 이용한 밀리미터파 대역 슬롯 도파관 안테나)

  • 이정수;성영제;김영식
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.15 no.4
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    • pp.353-359
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    • 2004
  • In this paper, the single-layer slotted waveguide array antenna is designed, which consists of two par the slot plate and the structure of waveguide. The key difficulty in mass production is the realization of perfect electrical contact between the two parts. Therefore the single-layer slotted waveguide array antenna is presented with a dumbbell patch and a choke. The choke can prevent from the leakage between the slot plate and waveguide, while the choke in the adjacent waveguide incurs space dissipation. To reduce the spacing of antennas about a dumbbell patch is utilized. the 16${\times}$16 array antenna gain of 27.2 ㏈ with 45 % aperture efficiency is obtained.

Miniaturized Radio Frequency Choke Using Modified Stubs for High Isolation in MIMO Systems

  • Lim, Seonho;Choi, Woo Cheol;Yoon, Young Joong
    • Journal of electromagnetic engineering and science
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    • v.15 no.4
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    • pp.219-223
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    • 2015
  • In this paper, a miniaturized radio frequency choke (RFC) using modified stubs is proposed to improve isolation characteristics in a multiple-input-multiple-output (MIMO) antenna system. The proposed RFC, based on the LC resonance, is designed to suppress the leakage current that leads to the degradation of antenna diversity performances in the MIMO antenna configuration. The proposed RFC is composed of two open stubs that are implemented on the top of the ground plane and miniaturized by adding a slit structure on the ground plane. The MIMO antennas are also designed to verify isolation performance in the LTE 2300 band (2,300-2,400 MHz). The MIMO antennas perform well with low reflection coefficient characteristics and high isolation characteristics in the whole LTE 2300 band. To evaluate the isolation in the MIMO system, the envelope correlation coefficient (ECC) is calculated, and the value is less than 0.08. The achieved ECC is regarded as a reasonable result for improving isolation performance in the frequency range of 2,300-2,400 MHz; also, radiation patterns of antenna elements are maintained regardless of the presence of RFC.

A Study of AM Broadcasting Antenna's Lightnning and Ground System (AM방송안테나의 낙뢰와 접지에 관한 연구)

  • 이문호
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.4 no.1
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    • pp.43-46
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    • 1979
  • The lightning which is occurred in different regions Contains 80% of whole between June and September. There were the lightning accidents at the peak of mountains. As a result, the antenna tower of AM broadcasting Systems build up clyish plain where has a low earth characteristics resistivity. The following have been observed as a Counter lightning Systems such as high frequency choke, sphere gap(75, 000 V/inch) and reflective power detection relay.

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Design of Broadband Polarization Diversity Antenna for Mobile Base Stations (이동 통신 기지국용 광대역 편파 다이버시티 안테나 설계)

  • Seo, In-Jong;Cho, In-Ho;Lee, Cheon-Hee;Jung, Jin-Woo;Lee, Hyeon-Jin;Lim, Yeong-Seog
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.21 no.9
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    • pp.1023-1029
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    • 2010
  • In this paper, we proposed the broadband polarization diversity antenna operating in the PCS, WCDMA and WiBro band for mobile base station. We designed the antenna using the dipole antenna of the square loop type and microstrip feeding structure. Additionally, we used the choke box to remove the distortion of radiation patterns by the reflector structure when operating broadband. The simulation was performed using MWS in a commercial tool of CST company and the antenna was fabricated on a teflon substrate with 3.33 of the relative permittivity. The proposed antenna has the bandwidth of 640 MHz(from 1.75 to 2.39 GHz) when VSWR is below 1.5. At the operating bands, the interisolation between the cross-pair radiators is less than -25 dB and the maximum gains for PCS, WCDMA and WiBro band are 8.9, 8.2 and 8.6 dBi, respectively.

GNSS Antenna PCO/PCV and Position Changes due to the Switch IGS08/igs08.atx to IGS14/igs14.atx

  • Choi, Byung-Kyu;Sohn, Dong-Hyo;Yoon, Ha-Su;Lee, Sang Jeong
    • Journal of Positioning, Navigation, and Timing
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    • v.11 no.2
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    • pp.83-89
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    • 2022
  • For precise GNSS applications, the antenna phase center correction (PCC) is absolutely required. The PCC magnitude can reach the centimeter level with the antenna structure. In the present study, we first investigate the phase center offset (PCO) and phase center variation (PCO) of three different antenna models in two different reference frames, IGS08/igs08.atx and IGS14/igs14.atx. Clear L1 and L2 PCO differences were found between IGS08 and IGS14. In addition, the PCV showed characteristics that is dependent upon the signal direction (azimuth and elevation angle). The remarkable thing is that the changes of a Dorne Margolin choke-ring antenna model (AOAD/MT DOME) was very small in two reference frames. In order to analyze changes in positions according to different reference systems, GNSS data obtained from DAEJ, SUWN, and TSKB stations were processed by the precise point positioning (PPP) method. We suggest that an antenna PCO/PCV can affect the precise GNSS positioning on the order of several millimeters in two different reference frames.

Design of Secant Pattern Radiator with Septum Circular Polarizer (격벽 구조형 원형 편파기의 시컨트 패턴 방사체 설계)

  • Yim, Jung-Min;Son, Jae-Ki;Lee, Taek-Kyung;Lee, Jae-Wook;Lee, Woo-Kyung
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.25 no.1
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    • pp.32-38
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    • 2014
  • In this paper, we design a secant pattern antenna combined with a septum circular polarizer to be used in the satellite data communications. To generate a radiation pattern with secant type, Fourier relationship between current distribution and space factor is applied and the circular symmetric structure of the aperture simplifies the design. The optimization process is performed by combining the radiator with the septum circular polarizer, and it is confirmed that the designed radiation pattern, axial ratio, and return loss characteristics satisfies the required performance of the antenna.

Implementation of an in vitro exposure system for 28 GHz

  • Lee, Young Seung;Dzagbletey, Philip Ayiku;Chung, Jae-Young;Jeon, Sang Bong;Lee, Ae-Kyoung;Kim, Nam;Song, Seong Jong;Choi, Hyung-Do
    • ETRI Journal
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    • v.42 no.6
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    • pp.837-845
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    • 2020
  • The objective of this study was to implement an in vitro exposure system for 28 GHz to investigate the biological effects of fifth-generation (5G) communication. A signal source of 28 GHz for 5G millimeter-wave (MMW) deployment was developed, followed by a variable attenuator for antenna input power control. A power amplifier was also customized to ensure a maximum output power of 10 W for high-power 28-GHz exposure. A 3-dB uniformity over the 80 mm × 80 mm area that corresponds to four Petri dishes of three-dimensional cell cultures can be obtained using a customized choke-ring-type antenna. An infrared camera is employed for temperature regulation during exposure by adjusting the airflow cooling rate via real-time feedback to the incubator. The reported measurement results confirm that the input power control, uniformity, and temperature regulation for 28-GHz exposure were successfully accomplished, indicating the possibility of a wide application of the implemented in vitro exposure system in the fields of various MMW dose-response studies.

A Study on the High-power Low-loss Dual Axes Waveguide Rotary Joint for Ka-Band Millimeter-Wave Small Radar (밀리미터파대역(Ka-대역)소형 레이더용 고 전력 저 손실 2축 도파관 로터리 조인트 연구)

  • Jung, Chae-Hyun;Sung, Jong-Hyun;Baek, Jong-Gyun;Lee, Kook-Joo;Park, Chang-Hyun;Kwon, Jun-Beom
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.18 no.1
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    • pp.91-96
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    • 2018
  • In this paper, dual axes waveguide rotary joint, which operates at high power and has low loss characteristic, is designed and fabricated for a Ka-band millimeter-wave small radar. Its electrical performance is verified through the S-parameter at room temperature, high power and operation temperature test. Rotary joint functionally consists of the mode converter transforming rectangular waveguide into circular waveguide and the choke at the rotation part. At the configuration design, linking a fixed transmitter to an antenna rotating dual axes electrically for minimum loss and light weight body are considered. In Fc(center frequency)${\pm}500MHz$, the designed rotary joint has VSWR 1.5:1 below return loss, -2.0 dB above insertion loss. It is found that rotary joint characteristics is similar to design results.

LTCC기술을 활용한 VCO모듈

  • 이영신;유찬세;이우성;강남기
    • The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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    • v.12 no.3
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    • pp.12-24
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    • 2001
  • The key advantage of LTCC(low temperature co-fired ceramics) technology is the ability to integrate passive components such as resistors, capacitors, and inductors. More compact circuits with an increased scale of integration are needed with the development for advanced telecommunication system such as IMT-2000. LTCC technology can be obtained by removing these elements from the substrate surface to inside of ceramic body. And it can miniaturize the wireless phone through integration of planar patch antenna, duplexer, band pass filter, bias line, circuit of impedance matching and RF choke etc. Futhermore, with the multilayer chip process and its outstanding electrical material characteristics, LTCC is predestined for highly-integrated, cost effective wide band applications. This paper focuses on the general description of LTCC MCM technologies and the fabrication of the multilayer VCO module.

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A Study of Threshold Determination of The GPS measurement failure using GPS Code-Carrier Divergence Test (GPS 의사거리-반송파 위상 측정치의 고장검출을 위한 임계값 결정 연구)

  • Son, Eunseong;Kim, Koon-Tack;Im, Sung-Hyuck;Lee, Eun-Sung;Heo, Moon Beom;Nam, Gi-Wook
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.24 no.1
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    • pp.10-15
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    • 2016
  • In this study, The code-carrier divergence test was applied to GPS measurements, and the results were compared and analyzed. The GPS data used for the threshold determination were obtained from Global Navigation Satellite System permanent stations built by the Korea Aerospace Research Institute. At each permanent station, identical dual-frequency receiver and choke ring antenna with radome are installed. The analysis method, root mean square values were compared and analyzed for each permanent station and satellite. As a result, the root mean square value generally decreased as the satellite elevation angle increased although the trend was gentle. Threshold were finally selected based on the average and standard deviation of root mean square for each permanent station. For improving of availability and continuity in real-time operation when the threshold is over the limits, Code-Carrier divergence test values are initialized.