• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.23 no.5
• /
• pp.559-569
• /
• 2012

In this paper, the X($1{\times}2$, 10.525 GHz) and K($3{\times}6$, 24.15 GHz) bands patch array antenna having single feed line for radar detector applications is proposed. The left side of the proposed array antenna is X band array antenna and the right is K band array antenna. Two array antennas with two stubs located in the front of antennas are fed through one transmission line. If the array antennas which have the different resonance frequency are fed by one transmission line using general T-junction, it interferes each other and the array antenna lost its character. Therefore, to prevent these interferences, two stubs using open and short property of stub are designed. First of all, the performances of array antenna weren't changed when each array antennas were connected with the stub and in the end, it is found out that it was the same when the two array antennas were combined and feed through the one transmission line. The measured gain at X band is 6.47 dBi and measured gain at K band is 13.07 dBi. The experimental results agree well with the simulated ones.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
• /
• 2001.02a
• /
• pp.142-144
• /
• 2001

We designed superconducting four-element patch array antenna which has single-feed circularly polarization and a resonance frequency of 11.85 GHz for DBS receiving system. Antennas have been fabricated from both gold conductor and $YBa_{2}$$Cu_{3}$$O_{7-x}$(YBCO) superconductor (thin films) for comparison. Simulated and measured results, and analysis on resonant frequency(fr), return loss, and bandwidth are presented.

• Journal of electromagnetic engineering and science
• /
• v.9 no.2
• /
• pp.66-70
• /
• 2009

The decode-and-forward cooperative communication protocol allows single-antenna users in wireless environments to obtain the powerful benefits of multi-antenna systems without the need for physical arrays. Evaluating the performance of this protocol through simulations is time-consuming and therefore, a need exists for an analytical BER expression to serve as a reference. This paper proposed such an expression for coherently BPSK-modulated data.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2001.10a
• /
• pp.250-254
• /
• 2001

본 문에서는 Tschebyscheff 다항식 이론을 이용하여 상대적 전류 분포비가 1:2:2:1이 되도록 마이크로스트립 패치 어레이 안테나(MPAA) 설계 제작하였다. 지향성을 갖는 제안된 안테나는 작고 가벼우며 얇다. 또한 빔폭이 14。 인 어레이 안테나이고, 중심 주파수는 10.2553GHz이다. MPAA는 한 개의 마이크로스트립 패치 안테나(SMA:single microstrip antenna)특성과 비교 분석하였다. 그 결과 MPAA는 SMA보다 보다 좁은 복사 전력 빔폭과 큰 최대 복사 전력 이득을 획득했다. PIN 다이오드를 이용한 위상 변환기를 적용하면 전자적 빔스케닝이 가능하고, 소형 레이더 시스템에 적합하다.

• Journal of electromagnetic engineering and science
• /
• v.5 no.3
• /
• pp.140-145
• /
• 2005

In this paper, an experimental investigation for return loss and a software-based prediction for interference level of single-packaged filtering antenna composed of dielectric waveguide filter and PCB(Printed Circuit Board) slot antenna in transceiver module have been carried out with several different feeding structures in millimeter-wave regime. The implementation and embedding method of the existing air-filled waveguide filters working at millimeter-wave frequency on general PCB substrate have been described. In a view of the implementation of each components, the dielectric waveguide embedded in PCB and LTCC(Low Temparature Co-fired Ceramic) substrates has employed the via fences as a replacement with side walls and common ground plane to prevent energy leakage. The characteristics of several prototypes of filtering antenna embedded in PCB substrate are considered by comparing the wideband and transmission characteristics as a function of bent angle of transmission line connecting two components. In addition, as an essential to the packaging of transceiver module working at millimeter-wave, miniaturization technology maintaining the performances of independent components and the important problems caused by integrating and connecting the different components in different layers are described in this paper.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.17 no.10 s.113
• /
• pp.1007-1019
• /
• 2006

In this paper, the synthesis method of multibeam radiation pattern with multi-directional beams and nulls is proposed. Genetic algorithm is applied for the optimization of amplitude and phase of the feeding signal into each element that is structured in planar array of single patch antenna with an arbitrary field distribution. To verify the validity of the proposed method, $2{\times}2$ planar array antenna is used for the measurement and the measured far field radiation pattern is compared with the simulation result. As a result, the synthesis of multibeam radiation pattern is implemented by the optimization of amplitude and phase of the feeding signal into each element of $8{\times}8$ planar array antenna system.

• International Journal of Aeronautical and Space Sciences
• /
• v.13 no.2
• /
• pp.250-259
• /
• 2012

The need for position information in indoor environments has been growing lately. Several indoor navigation systems have been studied. Among them, pseudolite-based indoor positioning systems are one of the best systems to obtain precise position measurements. However, the installation of such systems is very difficult because the calibration of pseudolite antenna position is complicated. For precise calibration, the use of carrier phase measurements is necessary, and whenever carrier phase measurements are considered, problems with cycle ambiguity appear. In this paper, a new approach to calibrate the positions of pseudolite antennas is proposed. By using a multi-antenna, the ambiguity can be eliminated, epoch by epoch, for every single carrier phase measurement. Moreover, the number of calibration points can be reduced down to 3 by use of measurements collected at unknown positions. Using the proposed methods, the process of the collection of carrier phase measurements becomes considerably simple and convenient. Simulation results are presented to verify the proposed algorithms.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.15 no.2
• /
• pp.195-202
• /
• 2015

As satellite communications services are showing gradual growth, so are the needs for dual or tri-band antennas greater than performance of conventional single-band antennas. In this paper, a simultaneously operable tri-band antenna for SATCOM(Satellite Communications) is proposed. It is different from conventional methods of implementing tri-band through replaceable horns, while it is designed with a tri-band feed assembly composed of corrugated and dielectric horns and reflectors of gregorian type to transmit and receive tri-band of X, Ku and Ka band simultaneously. And simulated and measured values were compared and analyzed for characteristics of the proposed antenna. In the results, radiation patterns of the proposed tri-band antenna were close to the simulated ones and also met specifications.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.20 no.3
• /
• pp.413-420
• /
• 2017

We investigate the performance of a true time delay(TTD) phase shifter to reduce the beam squint caused by frequency changes of a phased array antenna in wideband communication systems. To design a high gain phased array antenna, we need a long TTD, which causes high RF loss, low resolution and large dimension of TTD phase shifters. To overcome the problems, we propose a schematic of dual TTD phase shifters, which consists of short time delay(STD) in radio frequency(RF) part and long time delay(LTD) in intermediate frequency(IF) part. Our analysis results show that the proposed scheme reduces the required bits and delay time in RF band of the TTD compared to the conventional single TTD scheme.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.13 no.10
• /
• pp.1061-1070
• /
• 2002

In this paper, we present a performance analysis of the smart antenna test-bed operating in a IS2000 1x through a test-bed that has been implemented on a DSP(TMS320C6711) board. The test-bed consists of a PC (for generating the RX data), beam-former(i.e., a stand-alone PCB for weight computation), and an interfacing module. The performance improvements compared to a normal base station system consisting of a single antenna are shown in terms the BER(bit error rate) in the wide-band CDMA channel.