• Journal of the Korean Institute of Telematics and Electronics
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• v.3 no.3
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• pp.2-13
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• 1966

The impedance characteristics of vertical antennas over a finite image plane were analyzed and measured. Two kinds of image plane, one rectangular and the other circular, were used for the mesurements. And the length of antennas was varied at fixed frequency. All kinds of terminal zone effects which possible raise questions because of antenna mounting system were discussed. It is observed from the results that the measured impedance of antennas over a comparativley large rectangular plane is approximatly identical with the theoretical value, and also the impedance of antennas over a comparatively small circular plane had similar characteristics to a comparatively thick antennas over an inifinite image plane.

• Journal of Advanced Navigation Technology
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• v.27 no.6
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• pp.740-745
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• 2023

This study proposes the development of an antenna tracker system using a satellite system to stabilize the communication status of drones and extend the communication distance. The location information of the drone and the ground station was used to maximize communication gain in the general fixed antenna method between the ground station and the drone. We developed a tracker system that can automatically and continuously aim the ground station's antenna at the drone. It is expected that the use of antenna trackers will improve the stabilization of communication conditions and expand the communication distance, thereby leading to the advancement of the drone industry.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.1
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• pp.93-100
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• 2012

A telemetry signal occurs the line-of-sight problem by the effect of geography in flight test. A fixed relay system or a mobile relay system is used to solve that problem in general but we propose an airborne telemetry relay system using aircraft in this paper. An airborne telemetry relay system receives the telemetry signal of the test vehicle and then retransmits it to the ground system. The receiving antenna which is a phased array antenna can be tilted to ${\pm}30^{\circ}$ beam direction by beam-forming and track the rapidly moving test vehicle in effect. The relay pod which is mounted to an aircraft consists of the front antenna and the side antenna. It receives S-band signal and then down-converts the frequency to L-band signal. As a result, that can remove the frequency interference on an aircraft while retransmitting.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.5 s.96
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• pp.534-540
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• 2005

This paper analyzes the correlations between the impedance matching of the antenna and the radiation characteristics of the mobile handset body. Using two kinds of mobile handset which has retractable and fixed antenna the impedance and radiation pattern is measured under totally 16 conditions. By measured results, it has been identified that the radiation energy into human head can be reduced by attaining the better impedance matching when the radiation pattern out of the mobile handset is like the ideal monopole antenna.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.199.1-199.1
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• 2012

TRIO-CINEMA(TRiplet Ionospheric Observatory-Cubesat for Ion, Neutron, Electron & MAgnetic field)는 지구근접공간에서의 미세 자기장 변화 및 중성입자의 검출을 목적으로 경희대학교와 UC Berkeley가 공동 개발하는 초소형위성이다. 초소형위성은 내부 공간이 협소하여 효율적인 공간배치 및 위성체발사 시 진동에도 견딜 수 있도록 harness가 제작되어야 한다. CINEMA는 OBC, EPS, 배터리, 수신기, IIB(Instrument Interface Board), MAGIC(MAGnetometer Imperial College) board, HVPS(High Voltage Power Supply)로 구성된 avionics bus와 MAGIC, STEIN(Supra Thermal Electron, Ion, Neutral)의 payload, Solar panel, UHF와 S-band 안테나로 구성되어 있다. Solar panel에서 생산된 전력은 EPS를 통해 배터리에 저장되고 PC104를 통해 avionics stack의 각 board로 전력이 분배된다. IIB는 탑재체 파트와 연결되어 이를 제어하고 HVPS에서 STEIN에 공급되는 고전압은 특수 와이어를 통해 연결되며 UHF 안테나와 S-band 안테나는 RF 케이블로 수신기와 송신기가 연결되어 있다. 각각의 harness는 케이블타이와 lacing tape로 위성체와 고정되며 커넥터는 고정 지지대를 제작하여 나사로 체결하였다. CINEMA에 적용된 harness는 진동시험과 열진공시험을 통해 harness와 시스템의 안정성이 검증 되었다.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.2022-2024
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• 2004

본 논문에서는 초광대역 기술을 이용한 고정밀 위치 추적용 센서를 위한 소형, 저가의 안테나를 제안한다. 안테나는 Fat monopole 과 유사하지만, Fat monopole의 상대적인 협대역 특성을 개선하기 위해 탭을 부가하여 고주파에서의 특성을 향상시켰다. 또한 급전은 제작이 용이한 Coplanar 도파관 구조를 사용하였다. 검증을 위해 3.1GHz${\sim}$5.1GHz 대역에서의 고 정밀 위치 추적용 센서를 위한 안테나를 설계하였다. 상용 EM 프로그램을 사용하여 안테나의 치수들에 대한 최적화 작업이 이루어 졌다. 실제 제작 결과와 시뮬레이션 결과가 비교되었고 상당히 일치함을 확인 할 수 있었다. 제작된 안테나는 2.5GHz${\sim}$7GHz대역내에서 10dB이상의 Return loss를 가졌다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.10A
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• pp.980-989
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• 2002

In this paper, we have proposed the sectorization method of the adaptive sector antenna and the new receiver structure for the CDMA wireless multi-media communication which uses multi-code and single-code. The sectorization and average BER performance of the adaptive sector antenna, which employs the proposed sectorization method, are obtained through simulation. The simulation results have shown that the sizes of sectors are properly controlled according to the distribution of the load and that the BER performance of the adaptive sector antenna is enhanced much more than that of the fixed sector antenna. Also, we have proposed two receivers, which are different from the positions to detect multi-code signals, for the multi-media communication. Each receiver has a simple cancellation scheme and two adaptive sector antennas, which are called the 1st adaptive sector antenna and the 2nd adaptive sector antenna, respectively. In this paper, the average BER performances of the receivers are compared through simulation. As the results of the simulation, we have recognized that all user' BER performances are greatly dependent on the positions to detect the multi-code signals. When we consider both system complexity and terget BERs of signals, we have concluded that the receiver, which detect multi-code signals in the 1st and the 2nd adaptive sector antenna, is appropriate for the CDMA wireless multi-media communication systems.

• Journal of the Korean Society for Railway
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• v.18 no.2
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• pp.105-110
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• 2015

This paper presents a $4{\times}1$ beam-forming reader antenna system for a new type of RFID based train position detection technology. The required beamwidth of the reader antenna is analytically expressed for different train speeds. The proposed antenna system consists of four rectangular patch elements and two switching couplers which are designed, without any impedance matching networks, for two different antenna modes. The switching coupler is a rectangular quadrature coupler with Pin diodes connecting its center line and the ground plane. The beamwidth of the antenna when the diodes are off and on is $18^{\circ}$ and $39^{\circ}$, respectively. The proposed antenna system will be used for a real train test in the near future.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1B
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• pp.78-84
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• 2010

A fixed 900 MHz near field RFID system is developed to provide information; market efficiency, jewelry information and the circulation history information in real time, to the customers. The developed RFID system for the jewelry management consists of a reader, antenna and a CPU in a integrated type. The system size is $38\;{\times}\;25\;{\times}\;19\;cm^3$, the operated frequency band of the reader antenna is 905 ~ 926 MHz. The maximum gain of the embedded reader antenna is 5.1 dBii(@ 910 MHz). Honeycomb tag manufactured by RSI Co. is suitable for the jewelry management than another other commercial near field tags. The tagging method and the tagging location of Honeycomb tag are suggested. In the suggested system, the maximum reading range is about 16 cm, and the zone with 100 % recognition rate is 10 cm from the radom of the reader antenna.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.5
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• pp.3-8
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• 2013

We consider some adaptive iteration schemes that provide lower complexity of the iterative receiver by reducing unnecessary iterations. While conventional iterative receiver considers only fixed number of iterations, we apply adaptive iteration schemes, taking into account quality of the received frame. Based on simulation results, proposed schemes reduce average number of iterations while maintaining BER performance compared to the conventional scheme.