• 한국통신학회논문지
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• 제22권5호
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• pp.981-989
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• 1997

In this paper, the 5-element active phased array antennas coupled through slotline between elements are designed and fabricated. A recent studies on the active phased array antennas using the transmission line coupling which can be designed to provide strong coupling and the appropriate coupling phase. But this sturucture has limitation of expanding in two dimensions for planar active phased array antennas and distortion of the radiation pattern caused by coupling network. Thus our work proposes the slotline coupling structure asthe broadband coupling network for the active phased array antenna. In experiment, 5-elements active phased array antenas have steering range from -30.deg. to 20.deg. off broadside as the free-running frequencies of end elements are controlled. The overall results show that the proposed slotline coupling structure is suited for the coupling network in the actie phased array antenna system. And the proposed coupling structire solves the expansion problem and eliminates the distortion of the radiation pattern caused by the spurious radiation of the transmission line coupling network. Thus thiscan be expanded to two dimensional coupling network for the planar active phased array antenna system.

• 대한전자공학회논문지TC
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• 제46권12호
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• pp.44-51
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• 2009

핀 배열 안테나를 이용한 선형 위상 배열 안테나의 방사 특성을 일반적인 패치안테나를 이용한 선형 위상 배열 안테나와 방사 특성을 비교하였다. 핀 배열 안테나를 이용한 위상 배열 안테나는 단위 안테나간의 상호결합이 작게 발생하기 때문에 일반적인 패치안테나를 이용한 위상 배열 안테나의 성능보다 향상되었다. 핀 태열 안테나를 이용한 선형 위상 배열 안테나는 주빔의 방향에 따른 이득과 side lobe level 의 변화가 적은 우수한 방사 특성을 가진다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.519-522
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• 2002

An active phased array antenna consists of many channels. Each channel has a different initial phase shift and gain because of the inequality in the active circuits themselves, interface between radiators and active circuits, and beam-forming circuits and other antenna system configurations. This raises an inherent problem in active phased array antennas. To compensate for this problem the initial phase and gain of each channel should be calibrated. This paper presents an efficient calibration method for an initial phase variation of each channel in active phased array antennas. We tested our method in an active phased array antenna, and obtained good results in the radiation pattern and beam direction of antenna.

• 전기전자학회논문지
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• 제27권4호
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• pp.636-643
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• 2023

본 논문에서는 원전계 환경에서 위상배열안테나를 고속 보정하는 방법이 제안되었다. 원전계에서 수신된 전력만을 통해 각 안테나 요소를 보정하는 기존 rotating-element electric-field vector (REV) 방법을 간소화 한 최대값 보정 방법과, 각 안테나 요소가 아닌 부배열 단위로 묶어서 보정하는 방법이 제안되었다. PPO 알고리즘을 이용하여 위상배열안테나의 분포에 최적화된 파티셔닝을 찾고, 그에 따른 부배열 단위로 보정하여 기존 방법 대비 더 빠른 보정이 가능한 적응형 최대값 보정 방법이 제안 및 시뮬레이션 검증되었다. 보정이 이루어지는 동안 위상배열안테나의 이득이 더 높을 뿐 아니라, 형성되는 빔 패턴이 기존 방법보다 이상적인 빔 패턴에 더 가깝다.

• Journal of information and communication convergence engineering
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• 제18권4호
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• pp.254-259
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• 2020

Phased-array antennas comprise a demanding antenna design methodology for commercial wireless communication systems or military radar systems. In addition to these two important applications, the phased-array antennas can be used in beamforming for wireless charging. In this study, a four-way analog beamforming front-end module (FEM) for a hybrid beamforming system is developed for 2.4 GHz operation. In a hybrid beamforming scheme, an analog beamforming FEM in which the phase and amplitude of RF signal can be adjusted between the RF chain and phased-array antenna is required. With the beamforming and beam steering capability of the phased-array antennas, wireless RF power can be transmitted with high directivity to a designated receiver for wireless charging. The four-way analog beamforming FEM has a 32 dB gain dynamic range and a phase shifting range greater than 360°. The maximum output RF power of the four-way analog beamforming FEM is 40 dBm (=10 W) when combined the four individual RF paths are combined.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -2
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• pp.715-718
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• 2002

TX/RX dual microstrip 1$\times$8 sub-array antennas are designed, fabricated, and measured for a wideband array antennas in communications. They have a Right Handed Circular Polarization (RHCP) for TX from 7.9 to 8.4 GHz and Left Handed Circular Polarization (LHCP) for RX from 7.25 to 7.75 GHz. Two stacked patches are used for a wideband characteristics and cornertruncated square patches are adopted for a circular polarization. To enhance bandwidth characteristics of a circular polarization, 1$\times$2 sequential rotation arrays are applied. From the measured results, 1$\times$8 microstrip sub-array antennas have a good agreement with those of the simulation. Therefore the sub-array antennas are applicable to satellite communication antennas, active phased array antennas, and radiators in other antennas.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권11호
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• pp.521-528
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• 2003

A varactor diode was utilized in order to expand variable range of the natural oscillation frequency of an active phased-array antenna. We have conformed experimentally that the variable range of the natural oscillation frequency was expanded about three times in the oscillator controlled by the varactor diode. When frequency difference was given to the oscillators in the two elements antenna system, phase difference was appeared between the oscillators. The 2-, 3-, 5-elements patch antenna array was composed for the beam scanning experiments. All the above patch antennas showed good phased array characteristics. The experimental results are as follows that the scanning angle of the 2-elements array antenna is 28.6$^{\circ}$, the 3-elements array antenna is 29.4$^{\circ}$, and the 5-elements array antenna is 26.2$^{\circ}$.

• Journal of electromagnetic engineering and science
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• 제3권1호
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• pp.62-66
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• 2003

Novel coupled line phase shifters and its equivalent phase delay line for compact broadband phased array antennas are proposed. These phase control circuits are designed to be less complex, small size and to use a less number of active devices. The phase shifter is able to control a 120$^{\circ}$ phase shift continuously, and the phase delay line for a reference phase has a fixed 60$^{\circ}$ shifted phase. Both have the low phase error of less than $\pm$3.5$^{\circ}$ and the low gain variations of less than 1 ㏈ within the 300 MHz bandwidth. These proposed circuits are adequate to form the efficient beam-forming networks with compactness, broadband, less complexity, and low cost.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권3호
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• pp.175-181
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• 2004

In order to increase the coupling efficiency of the Power and Phase of the active Phase way antenna, we have fabricated the active phased-array antenna which is coupled by the transmission line, and investigated the relationship between the length of the coupling transmission line and coupling power and phase. The following three types of driving method -(1) giving the frequency difference between the two active antenna, (2) applying the input signal to the one side of the two antennas, and changing the eigen frequency of the other side antenna, (3) appling the different phase inputs to the active antennas was investigated. The experimental results showed that the interval of the antenna elements has not affected the power and the phase of the antenna.

• Journal of information and communication convergence engineering
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• 제13권2호
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• pp.81-85
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• 2015

A 94-GHz phased array antenna using a log-periodic antenna has been developed on a GaAs substrate. The developed phased array antenna comprises four log-periodic antennas, a phase shifter, and a Wilkinson power divider. This antenna was fabricated using the standard microwave monolithic integrated circuit (MMIC) process including an air bridge for unipolar circuit implementations on the same GaAs substrate. The total chip size of the fabricated phased array antenna is 4.8 mm × 4.5 mm. Measurement results showed that the fabricated phased array antenna had a very wide band performance from 80 GHz to 110 GHz with return loss characteristics better than -10 dB. In the center frequency of 94 GHz, the fabricated phased array antenna showed a return loss of -16 dB and a gain of 4.43 dBi. The developed antenna is expected to be widely applied in many applications at W-band frequency.