• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.5
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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.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.12
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• pp.44-51
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• 2009

The radiation characteristics of a pin array patch antenna phased array are compared to those of a conventional patch antenna phased array. The performance of a pin array patch antenna phased array is much improved than that of a conventional patch antenna phased array because the mutual coupling between the adjacent pin array patch antennas is very small compared to that between the adjacent conventional patch antennas. The radiation characteristics of a pin array patch antenna phased array show the superior performance such as low variation of the gain of the main beam and the side lobe level for the variation of the direction of the main beam.

• Proceedings of the IEEK Conference
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• 2002.07a
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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.

• Journal of IKEEE
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• v.27 no.4
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• pp.636-643
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• 2023

In this paper, a high-speed calibration method for phased array antennas in the far-field is presented A max calibration, which is a simplification of the rotating-element electric-field vector (REV) method that calibrates each antenna element only through received power, and a method of grouping calibrations by sub-array unit rather than each antenna element were proposed. Using the Proximal Policy Optimization (PPO) algorithm, we found a partitioning optimized for the distribution of phased array antennas and calibrated it on a subarray basis. An adaptive max calibration method that allows faster calibration than the conventional method was proposed and verified through simulation. Not only is the gain of the phased array antenna higher while calibration is being made to the target, but the beam pattern is closer to the ideal beam pattern than the conventional method.

• Journal of information and communication convergence engineering
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• v.18 no.4
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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.

• Proceedings of the IEEK Conference
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• 2002.07b
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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.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.11
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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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• v.3 no.1
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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.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.3
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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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• v.13 no.2
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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.