• Journal of the Korea Institute of Military Science and Technology
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• v.6 no.3
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• pp.113-121
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• 2003

In this paper, the transmit antenna for the space feeder used for the phased array antennas is investigated. The multi-aperture horn antenna is proposed as the transmit antenna and the characteristics are verified with the Matlab coding, HFSS of Ansoft Corp., and MWS of CST Corp., The E-plane and H-plane beam patterns of the multi-aperture horn antenna are nearly symmetrical and the sidelobe level of the I-plane beam pattern is lower than that the of general pyramidal horn antenna. The fabricated multi-aperture horn antenna is measured using the near-field measurement system. The measured results show good agreement with the simulated ones.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.6
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• pp.1130-1141
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• 2015

Conventionally, a pulse radar is used for middle-sized or large-sized ships to detect other ships or obstacles located at a long distance. However, it is hardly equipped for most of the small-sized ships due to mounting and maintenance costs. Therefore, FMCW(frequency modulated continuous wave) radar is suggested as an alternative for the small-sized ships. Since it operates with low power and has good range resolution for relatively close objects, it is eligible for the small-sized ships. In previously proposed FMCW radar system, it only estimates distance and velocity of a target ship placed in the direction of main beam and is hard to detect several ships simultaneously. Thus, we suggest the method for detecting several ships at the same time by applying MUSIC(multiple signal classification) algorithm to FMCW radar signal received by a phased array antenna. In addition, by combining digital beam forming with the MUSIC algorithm, better angle resolution is achievable.

• Smart Media Journal
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• v.9 no.4
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• pp.60-65
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• 2020

The monopulse tracking algorithm can estimate the location of a partner station based on an RF (Radio Frequency) signal. The location of the partner station is estimated based on the monopulse ratio curve (MR-C), which is calculated based on the sum and difference signal patterns of an antenna. Therefore, the range in which the estimated location can be calculated with high accuracy increases in proportion to the linear region of MR-C. In this paper, we proposed a method to extend the linear region of the MR-C curve using the beamforming technique for the tracking antenna system using the active phased array antenna. Simulation results based on the same antenna system, it was confirmed that the linear region of MR-C was enlarged by about twice as much as the general case where the proposed method was not applied.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.10
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• pp.1089-1097
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• 2002

In this paper, the novel shipboard Active Phased Array Antenna(APAA) system for maritime mobile satellite communications is introduced. The antenna uses novel technologies like wide range hybrid tracking, single antenna elements with both of Rx and Tx, asymmetrical array structure, interference isolation between Rx and Tx, and error correction method from frequency scan effect. The antenna has single aperture for both of Rx and Tx with 32 $\times$ 4 two-dimensional array. The antenna has two beams. Its frequencies are 7.25 ~ 7.75 GHz for Rx and 7.9 ~ 8.4 GHz for Tx. The antenna gains are 35.4 dBi for Rx and 35.7 dBi for Tx, those are 54 % of efficiency. The electrically steering ranges are $\pm$35$^{\circ}$ of elevation direction and $\pm$4$^{\circ}$ of azimuth direction. The mechanical control ranges at hybrid tracking capability are continuous 360$^{\circ}$ of azimuth direction and $\pm$10$^{\circ}$ of elevation direction. The antenna has 2.2$^{\circ}$ of 3 dB beamwidth, -14 dB of sidelobe level, and 21 dB of cross-pol suppression. The antenna performance was measured by near field measurement set. Its system performance was tested on the ship motion simulator and with the satellite transponder simulator. The test result showed that its tracking error was within -3 dB from its peak gain under motion condition. The antenna system was tested by real modulated Direct Broadcasting Satellite(DBS) signals to check its communication processing function.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.9
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• pp.808-816
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• 2016

In this paper, a new technique and cost function which can be to classify jamming signal and target signal from the spectral distribution of received signal in order to minimize the main beam distortion of target signal and to form nulls in the direction of jamming signal in array antennas of single port system is proposed. The proposed cost function is applied to the adaptive algorithm which has the fast convergence and stable nulling performance through the combination of the PSO(Particle Swam Optimization) algorithm and the gradient-based perturbation algorithm, which shows stable nulling performance adaptively even under the moving jamming signal where the incident direction of the jamming signal is changing with time.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.2
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• pp.321-326
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• 2018

This study describes the design and implementation of TRM(Transmit and Receiver Module) for detection for targets of small RCS(Radar Cross Section). Through the pre-simulation analysis of radar system about RF, the main specifications of TRM are verified. After the fabrication of TRM, the main characteristics such as the maximum output, noise figure, spurious were confirmed. In the future, the radar system test will be carried out by assembling TRMs, antenna radiator, and the transceiver that generates and receivers the radar waveform reflected.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.881-885
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• 2008

Wireless energy transmission system to a Micro Aerial Vehicle is now under development. A 5.8 GHz microwave phased array antenna and rectenna array receiver have been developed. An electric motor on a circling MAV model was driven by the transmitted power. In addition, 140GHz millimeter-waves of up to 1MW was beamed to a "Microwave Rocket" and its thrusting has been successfully demonstrated.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.7
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• pp.26-36
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• 2014

The needs of active phased arrays antenna system is getting more increased for IMT-Advanced system efficiency. The active phased array structure consists of lots of small transceivers and radiation elements to increase system efficiency. The minimized module of high efficiency transceiver is key for system implementation. The power amplifier of transmitter decides efficiency of base-station. In this paper, we design and implement minimized module of high efficiency transceiver for IMT-Advanced active phased array system. The temperature compensation circuit of transceiver reduces gain error and the analog pre-distorter of linearizer reduces implemented size. For minimal size and high efficiency, the implented power amplifier consist of GaN MMIC Doherty structure. The size of implemented module is $40mm{\times}90mm{\times}50mm$ and output power is 47.65 dBm at LTE band 7. The efficiency of power amplifier is 40.7% efficiency and ACLR compensation of linearizer is above 12dB at operating power level, 37dBm. The noise figure of transceiver is under 1.28 dB and amplitude error and phase error on 6 bit control is 0.38 dB and 2.77 degree respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.10
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• pp.1061-1070
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• 2009

In this paper, we have designed TDL(True-time Delay Line) for eliminating beam-squint occurring in active phased array antenna with large electrical size operated in wide bandwidth, and have tested its electrical performance. The proposed TDL device is composed of 4-bit microstrip delay line structure and MMIC amplifier for compensation of the delay-line loss. The measured results of gain and phase versus delay state satisfy the electrical requirements, also P1dB output power and noise figure meet the requirement. To verify the performance of fabricated TDL, we have simulated the beam patterns of wide-band active phased array antenna using the measured results and have certified the beam pattern compensation performance. As a result of simulated beam pattern compensation with respect to the 675.8 mm size antenna which is operated in X-band, 800 MHz bandwidth, we have reduced the beam squint error of ${\pm}1^{\circ}$ with ${\pm}0.1^{\circ}$. So this TDL module is able to be applied to active phase array antenna system.

• The Journal of the Acoustical Society of Korea
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• v.29 no.6
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• pp.355-364
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• 2010

Considering biological safety, it is very important to measure acoustic power from ultrasonic array probe for diagnostic ultrasound imaging applications. In this paper, to measure acoustic power from each element on array probe for ultrasonic diagnostic equipment, we reconstruct and automate the acoustic power measurement system. The acoustic power from linear, phased and curved array were measured and analyzed. As a result of measurement, the effects caused by directivity of sound beam from curved array were founded. To remove these effects, we developed and applied the correction model. The proposed system is useful to evaluate characteristics of the acoustical output power of array probe.