• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.7B
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• pp.891-894
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• 2001

본 논문에서는 능동 배열 안테나에서 RF 대신 중간주파수를 이용하여 빔 추적을 하는 방법이 연구되었다. 안테나의 각 배열은 전압제어 발진기, 위상추적기, 혼합기와 결합되어 있으며 혼합기는 안테나 상에서 직접 RF 신호를 직접 중간주파수 신호로 변환시킨다. 전압제어 발진기 입력은 위상추적기에 의하여 조절되며 배열 안테나의 주사범위는 위상추적기와 전압제어발진기에 의하여 결정되었다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.689-692
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• 2005

In this paper, we have developed a retrodirective active array operating in the 2 GHz LS band. The retrodirective array has the property of re-directing any electromagnetic wave back to the incoming direction without any priory informations. The system is consisted of frequency mixers and antenna array. The mixer is acting as a phase conjugator. In this research, 2-port gate mixers using pHEMT and 1${\times}$4 monopole array have been used. The retrodirective array developed in this research can be applied in the base station facilities for the wireless mobile communications and RFID transponders.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.1
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• pp.171-175
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• 2006

In this paper, we have developed a retrodirective active array operating in the 2 GHz LS band. The retrodirective array has the property of redirecting any electromagnetic wave back to the incoming direction without any priory informations. The system is integrated with phase conjugators and antenna array. Microwave phase conjugators can be implemented by microwave mixers. In this research, 2-port gate mixers using pHEMT and $1{\times}4$ monopole array have been used to achieve the retrodirectivity. The measured results have been compared with the theoretical prediction, and it has been shown that there exists a reasonable agreement between them. The monopole array can be used easily in many areas for simplicity and cost-effective property, and the retrodirective array developed in this research can be applied directly in the base station facilities for the wireless mobile communications. indoor wireless LAN and RFID transponders.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.59-63
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• 2004

In this paper, we have developed a 2-port resistive frequency mixer for the retrodirective active array. The circuit topology is consisted of 2-port to avoid the complexity of LO and RF signal combination, using a pseudomorphic HEMT device. The operating frequencies are 4.0 GHz, 2.01 GHz, and 1.99 GHz for LO, RF, and IF, respectively. Conversion loss is measured to be -1㏈ and 1-㏈ compression point -15 ㏈m at the LO power of -10 ㏈m.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.1
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• pp.9-18
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• 2021

The 5G communication system employs the millimeter wave with the extremely high frequency. Since the high frequency signal has the strong straightness, the beamforming technology based on the multiple base stations is required for services covering wide range. The beamformer needs the angle-of-arrival(AOA) information of the signal incident to the antenna, and it is generally estimated through the high resolution AOA estimation algorithm such as Multiple Signal Classification (MUSIC) or Estimation of Signal Parameters via Rotational Invariacne Technique (ESPRIT). Although various antenna array shapes can be employed for the beamformer, a single shape (square, circle, or hexagonal) is typically utilized. In this paper, we introduce a transmitting/receiving beamforming system based on the combined array antenna with square and circular shapes, which is proper to various frequency signals, and evaluate its performance. For evaluating the performance of the proposed beamforming system based on the combined array antenna, we implement the computer simulation employing various scenarios.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.2
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• pp.397-401
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• 2005

In this paper, we have developed a frequency mixer which can be used as a microwave phase conjugator in the retrodirective array antenna. The retrodirective array, which can reflect the incident wave retrodirertively back to the source direction without any priori information, requires phase conjugators to achieve the phase change of 180 degrees for the incoming signal. frequency mixers can efficiently serve as phase conjugators. The circuit topology is of the 2-port structure to avoid the complexity of LO and Rf signal combination and matching circuits, using a pseudomorphic HEU device. The operating frequencies are 4.0 CHz, 2.01 CHz, and 1.99 CHz for LO, RF, and If signals, respectively. Conversion loss is measured to be -ldB and 1-dB compression point -l5 dBm at the LO power of -10 dBm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.7
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• pp.1053-1064
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• 1999

In this paper, to transmit and receive the differently polarized signals simultaneously with a single antenna system, the dual-frequency microstrip array antenna with dual-polarization is proposed and designed. This antenna operates simultaneously at 14.25 GHz and 12.50 GHz. To extend to two dimensional array, microstrip feed line and coaxial probe through via-hole used.

• Journal of Advanced Navigation Technology
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• v.27 no.3
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• pp.281-286
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• 2023

This paper proposes a design of a wideband array antenna involving the downlink bands of fixed satellite service (FSS) and broadcasting satellite service (BSS) by applying two mixed patch sets. The proposed antenna is implemented on FR4 substrate by arranging rectangular patches in 6 by 2. To design a wideband antenna (10.7~12.75 GHz) covering both FSS downlink bands (10.7~10.95 GHz, 11.2~11.45 GHz) and BSS downlink bands (11.7~12.5 GHz, 12.2~12.75 GHz, 11.7~12.2 GHz), rectangular patches working at 11.5 GHz and 12.5 GHz are arranged alternately, and thus the proposed antenna can obtain a wide bandwidth equivalent to 30.8% of the center frequency. The proposed antenna was fabricated and measured, and the results are well matched with the simulated ones. From the performances, the proposed antenna can be applied to the receiving antenna for FSS and BSS downlinks.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.5
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• pp.853-859
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• 2007

This paper presents a microstrip patch array antenna having transmission feed and reception feed for satellite communication in the Ku band. In this paper, the element of the patch array antenna is a three-stacked structure consisting of one radiation patch and two parasitic patches for high gain and wide bandwidth characteristics. To obtain higher gain, the unit elements are expanded into a $1{\times}8$ may using a mixture of series and parallel feeds. The proposed antenna has horizontal polarization for the Rx band and vertical polarization for the Tx band. To verify the practicality of this antenna, we fabricated a three-stacked patch array antenna and measured its performance. The gain of the array antenna in the Rx and Tx bands exceeds 17 and 18 dBi, respectively. The impedance bandwidth is over 10 % in both bands. The cross-polarization level is below -25 dB, and the sidelobe level is below -9.4 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.3
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• pp.379-387
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• 2000

In this paper, to transmit and receive the differently polarized wideband signals simultaneously with a single antenna system, the wideband, dual-frequency and dual-polarized(WDFDP) microstrip array antenna is proposed and designed. This antenna operates simultaneously at 14.25 GHz and 12.50 GHz. To extend to two dimensional array, microstrip feed line and coaxial probe through via-hole are used. The experimental results show that the proposed WDFDP microstrip antenna can be used in the compact portable terminals with a single antenna system and the characteristic of the resonators in this antenna produces a greatly enhanced bandwidth.