• 전기학회논문지
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• 제56권1호
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• pp.161-166
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• 2007

In this paper, two 4$\times$4 rectangular patch array antennas operating at 20 GHz are implemented for the satellite communication. The sixteen patch antennas and microstrip feeding line are printed on a single-layered substrate. The design goal is to achieve high directivity and gain by optimizing design parameters through permutations in element spacing. The spacing between the array elements is chosen to be 0.736$\lambda$. Numerical simulation results indicate that the HPBW(Half-Power Beam Width) of the 4$\times$4 patch array antenna is 18.78 degrees in the E-plane and 18.48 degrees in the H-plane with a gain of 17.18 dBi. Numerical simulations of a 4$\times$4 recessed patch array antenna yield a HPBW of 18.71 degrees in the E-plane and 17.82 degrees in the H-plane with a gain of 19.43 dBi.

• 한국정보통신학회논문지
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• 제24권9호
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• pp.1165-1171
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• 2020

본 논문에서는 28 GHz와 38 GHz의5G 단말용 안테나 타입별 반사손실, 방사패턴 등의 성능을 고려하여 단일안테나를 설계하고, 안테나 소자를 반 파장 간격으로 배열하여 5G 단말용 배열안테나를 설계하였고 성능을 분석하였다. 밀리미터파 대역 통신에서는 기존의 마이크로파 대역에서와는 달리 송수신 간의 높은 경로손실이 발생한다. 5G 밀리미터파 단말용 배열안테나 설계에서는 안테나의 이득, 대역폭뿐만 아니라, 안테나 소자 간 격리도, side-lobe level(SLL) 등의 안테나 성능이 추가적으로 고려되어야 한다. 28GHz와 39GHz에서 제안하는 안테나 이득이 각각 약 13.5dBi 와 11.3dBi, 반사손실도 -18.4 dB과 -20 dB 이하의 측정 결과로부터 설계의 타당함을 입증하였고, 밀리미터파 대역 응용으로서도 적합함을 보였다.

• 한국전기전자재료학회논문지
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• 제17권7호
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• pp.770-775
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• 2004

Although $High-T_c $superconducting HTS antennas have high efficiency and high gain, narrow bandwidth due to the high Q is the major limitation for application of satellite communication and mobile communication. Defining bandwidth as the frequency range over which standing wave ratio (SWR) is 2:1 or less, HTS antenna bandwidths are typically less than 1 %. Thus considerable effort has been focused on developing HTS antennas for broadband operation. In this work the HTS antenna array, using the bipin antenna which consisted of two triangle-radiation patches, was designed and fabricated using a ${YBa}_2{Cu}_3{O}_7x (YBCO)$ superconducting thin film on a MgO substrate for broadband operation. Also gold antennas with the same dimension as our HTS antennas were fabricated on the MgO substrate for the comparison. Experimental results for both antennas were reported in terms of radiation patterns, return losses, bandwidths and other various characteristics. The center frequency of HTS antennas was 20.28 GHz and the bandwidth obtained was significant 10 %.

• 한국통신학회논문지
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• 제26권12B호
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• pp.1724-1732
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• 2001

본 논문에서는 평행 결합 선로 형태의 광대역 임피던스 정합 회로를 이용하여 마이크로스트립 배열 안테나의 좁은 대역폭을 개선할 수 있는 방법을 제안하였고, 평행 결합 선로가 부착된 여러 형태의 광대역 마이크로스트립 배열 안테나들을 설계하여 그 특성을 비교 분석하였다. 그리고 평행 결합 선로 형태의 광대역 임피던스 정합 회로를 구현하기 위한 분포 회로 방식의 반복적인 방법을 제시하였다. 본 논문에서 제시된 평행 결합 선로가 부착된 마이크로스트립 배열 안테나는 일반적인 마이크로스트립 배열 안테나와 크기는 동일하게 유지하면서 대역폭은 약 1.7배까지 증가하였고, 대칭적인 급전 구조를 사용하여 낮은 교차 편파 크기도 유지할 수 있다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 ICEIC The International Conference on Electronics Informations and Communications
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• pp.302-309
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• 2004

The transmission capacity of wireless communication systems may become dramatically high by employ multiple transmit and receive antennas with space-time coding techniques appropriate to multiple transmit antennas. For large number of transmit antennas and at high bandwidth efficiencies, the receiver may become too complex whenever correlation across transmit antennas is introduced. Reducing decoding complexity at receiver by combining array processing and space-time codes (STC) helps a communication system using STC to overcome the big obstacle that prevents it from achieving a desired high transmission rate. Multi-carrier CDMA (MC-CDMA) allows providing good performance in a channel with high inter-symbol interference. Antenna array, STC and MC-CDMA system have a similar characteristic that transmit-receive data streams are divided into sub-streams. Thus, there may be a noticeable reduction of receiver complexity when we combine them together. In this paper, the combination of array processing and STC in MC-CDMA system over slow selective-fading channel is investigated and compared with corresponding existing MC-CDMA system using STC. A refinement of this basic structure leads to a system design principle in which we have to make a trade off between transmission rate, decoding complexity, and length of spreading code to reach a given desired design goal.

• 한국기계가공학회지
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• 제21권1호
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• pp.73-80
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• 2022

Sensors are applied to small aviation platforms for various purposes. Radio frequency (RF) antennas, which are representative sensors, are available in many forms but require the application of slot array RF antennas to ensure high performance and designation. Slot RF array antennas are applied to dip brazing techniques, but the yield and production time are determined by the proficiency of production personnel in a labor-intensive form. Unmanned aerial vehicles or drones, which are representative small aviation platforms, are continuously exposed to various random vibrations because propellers and multiple power sources are used in them. In this study, the fatigue life of slot array RF antennas applied with additive manufacturing was evaluated through the cumulative damage method (Miner's rule) in a vibration environment with a small aviation platform. For the evaluation, an S N curve obtained from a fatigue strength test was used.

• 디지털산업정보학회논문지
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• 제15권1호
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• pp.67-76
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• 2019

Despite attractive advantages such as good time-frequency localization and improved spectral efficiency, filter bank multicarrier with offset quadrature amplitude modulation (FBMC/OQAM) suffers from multipath fading. In highly frequency-selective channels, the effect of multipath interference can significantly distort the FBMC/OQAM signal due to the absence of cyclic prefix. To resolve the problem of the multipath interference in FBMC/OQAM, this paper proposes applying an antenna array that provides well shaped beam pattern for each multipath. To evaluate the performance of the proposed array system, various computer simulations have been conducted. The accuracy of direction of arrival estimation is demonstrated through spatial spectrum for a different number of antennas in a sub-array. The performance improvement is presented in terms of bit error rate. We found that the proposed array system mitigate the multipath interferences in Extended Typical Urban model with 12 antennas in a sub-array. Moreover, as the number of antennas in a sub-array increases, the system provides a signal-to-noise ratio gain.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권8호
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• pp.4006-4020
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• 2018

In recent years, one of the most remarkable 5G technologies is massive multiple-input and multiple-output (MIMO) system which increases spectral efficiency by deploying a large number of transmit-antennas (eg. tens or hundreds transmit-antennas) at base station (BS). However, conventional massive MIMO system using single-polarized (SP) transmit-antennas increases the size of the transmit-array proportionally as the number of transmit-antennas increases. Hence, size reduction of large-scale transmit-array is one of the major concerns of massive MIMO system. To reduce the size of the transmit-array at BS, dual-polarized (DP) transmit-antenna can be the solution to halve the size of the transmit-array since one collocated DP transmit-antenna deploys vertical and horizontal transmit-antennas compared to SP transmit-antennas. Moreover, proposed DP massive MIMO system increases the spectral efficiency by not only in the space domain but also in the polarization domain whereas the conventional SP massive MIMO system increases the spectral efficiency by space domain only. In this paper, the comparative performance of DP and SP massive MIMO systems is analyzed by space division multiple access (SDMA) and space-polarization division multiple access (SPDMA) respectively. To analyze the performance of DP and SP massive MIMO systems, DP and SP spatial channel models (SCMs) are proposed which consider depolarized propagation channels between transmitter and receiver. The simulation results show that the performance of proposed 32 transmitter (Tx) DP massive MIMO system improves the spectral efficiency by about 91% for a large number of user equipments (UEs) compare to 32Tx SP massive MIMO system for identical size of the transmit-array.

• 대한전자공학회논문지TC
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• 제45권10호
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• pp.80-89
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• 2008

패치와 접지면 사이에 삽입된 핀 배열을 가지는 패치안테나 (핀 배열 패치안테나)를 제작하고 특성을 측정하였다. 핀 배열 패치안테나가 일반적인 패치 안테나와 비교하여 E-평면의 수평방향으로 방사는 약 10 dB 이상 억제되고 H-평면의 수평방향으로 방사도 약 4 dB 이상 억제됨을 볼 수 있었다. 또한 전방으로의 방사는 증가하고 후방으로의 방사는 감소하여 안테나의 지향성이 향상됨을 볼 수 있었다. Half-power beamwidth가 E-평면 과 H-평면 모두에서 대폭 작아져 방사패턴 특성이 향상됨을 볼 수 있었다. 핀 배열 패치안테나에 삽입하는 핀 반경을 증가시키면 공진 주파수가 증가함을 볼 수 있었다. 또한 기판의 특성에 따라 수평방향으로의 방사억제 효과가 최대가 되는 최적 핀 반경 값이 존재함을 볼 수 있었다.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2002년도 종합학술발표회 논문집 Vol.12 No.1
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• pp.263-267
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• 2002

For driver's convenience, the ACC (Adaptive Cruise Control) requires a system which controls the vehicle to keep the distance among the automobiles constant. This paper describes the microstrip array antennas designed to operate at 24 GHz, and used as a direction indicator of moving vehicles. $8{\times}2$ transmit away antenna with wide beamwidth, $8{\times}4$ receive center array antenna, and two $8{\times}8$ receive array antennas with narrow beamwidth were designed. The measured result shows that the designed array antennas arc suitable fur detecting 3 directions of the vehicle when the scan angle is within the restricted area.