• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.3
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• pp.48-55
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• 2006

This paper describes the antenna based GPS anti-jamming technology called CRPA(Controlled Reception Pattern Antenna), which used $2{\times}2$ array elements. In this system, the main functions are the antenna complex weight control and the GPS digital I/Q VM(Vector Modulator). To update the VM's I/Q complex weights, the PC based DAC(Digital to Analog Converter) module was also used and the two analog output voltages were applied to the $2{\times}2$ array elements to synthesize the null pattern. In the study, we also simulated the $2{\times}2$ GPS array null patterns to compare the null depth with experimental results. The VM was also modified at the frequency of 1.575GHz for the GPS L1 and controlled by the PC based VM software.

• ETRI Journal
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• v.24 no.3
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• pp.197-204
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• 2002

This paper presents the results of the numerical simulation of a multibeam active phased array antenna for a High Altitude Platform Station (HAPS). The simulation takes into account the random errors caused by the non-identity of the array elements and the inaccuracy of the antenna calibration. The results of our statistical simulation show that the strict requirements on the sidelobe envelope for HAPSs can be met when the amplitude and phase distribution errors are minor, a condition which may be achieved by using digital beamforming.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.11
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• pp.1264-1271
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• 2012

Fast tracking is important for high-speed data transmission in high-speed mobile environment such as high speed rail and vehicular. Digital retrodirective array antenna is possible to do automatically beam tracking because it can control the phase information of the output signal toward opposite direction to input signal without no a priori knowledge of the arrival direction. Also, Digital retrodirective array antennas has merit that it is easy to upgrade and modify compare with analogue retrodirective array antennas. In this paper, we analyze the BER performance of digital retrodirective array antenna under AWGN environment and multipath signal. Simulation results show correct phase estimation and conjugation of retrodirective array antenna by using phase detector block. Also, phase conjugation technique has better BER performance about 1 dB at source than that of without phase conjugation when phase lag is $15^{\circ}$ in AWGN environment. This paper also discusses effect of the presence of multipath signal. Phase and amplitude error about direction of direct signal occurs when retrodirective array system is affected by interference and multipath signal in the presence of multipath signal.

• Journal of Korea Society of Digital Industry and Information Management
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• v.5 no.1
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• pp.83-88
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• 2009

This paper consider the problem of direction of arrival(DOA) estimation in the presence of multipath propagation. The sensor elements are assumed to be linear and uniformly spaced. Numerous authors have advocated the use of a beamforming preprocessor to facilitate application of high resolution direction finding algorithms The benefits cited include reduced computation, improved performance in environments that include spatially colored noise, and enhanced resolution. Performance benefits typically have been demonstrated via specific example. The purpose of this paper is to provide an analysis of a beamspace version of the MUSIC algorithm applicable to two closely spaced emitters in diverse scenarios. Specifically, the analysis is applicable to uncorrelated far field emitters of any relative power level, confined to a known plane, and observed by an arbitrary array of directional antenna. In this paper, we researched about optimize beam forming to smart antenna system. The covariance matrix obtained using fourth order cumulant function. Simulations illustrate the performance of the techniques.

• Journal of Korea Society of Digital Industry and Information Management
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• v.13 no.3
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• pp.75-81
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• 2017

This paper estimate a desired signal in a correlation wireless communication. The transmitted signal is mixed with the information signal, interference, and noise in wireless channel, and it is incident on the receiver. In this paper, we apply MUSIC algorithm and sub-array method to recover the total rank of the correlation matrix in order to estimation a desired signal among receiving signals. Through simulation, we analyze to compare the proposed method with the classical MUSIC algorithm. As a result of the simulation, the proposed method improved the resolution about 10degrees compared to the conventional MUSIC algorithm. We prove the superiority of the proposed method for the desired signal estimation in correlation channel.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.8C
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• pp.745-757
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• 2007

In this paper, we propose a design of GPS anti-jamming system and its operational method, which can effectively suppress interference and jamming signals induced in GPS receiver. The 7-array antenna used in the proposed system is composed of conventional 6 equi-spaced circular elements with one element on the center of antenna and can be efficiently operated under power-constrained conditions. Futhermore, in this paper, we analyze the structure and complexity of STAP and SFAP which are well known techniques in adaptive array antenna signal processing, and we compare the BER performances between STAP and SFAP in various jamming environment based on the same complexity.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.11
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• pp.857-867
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• 2018

Active array radar is evolving into digital active array radar. Digital active array radar has many advantages for making several simultaneous radar beams from the digital receive data of each element. A digital-type transceiver(TR) module is suitable for this goal in radar. In this work, the design results of an L-band digital TR module are presented to verify the possibility of fabrication for a digital active array antenna. This L-band digital TR module consists of a gallium-nitride-type HPA to achieve a more than 350-W peak output power and one-chip transceivers that include a digital waveform generator and analog digital converter. The receiving gain was 47 dB, the noise figure was less than 2 dB, and the final output type of the four channel receiving paths was one optic signal.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.12
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• pp.924-934
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• 2018

This paper describes the development and measurement results of C-band planar active phase array antenna for detecting and tracking radar(weapon-locating radar). The antenna is designed with 14 sub-arrays(12 main channels and 2 sidelobe blanking channels and approximately 3,000 elements of transmit-receive channel) to generate transmit and digital receive patterns. Using a near-field measurements facility, G/N, transmit patterns, and received patterns are measured. Receive patterns are implemented with digital beamforming by signal processing. The measurement results demonstrate that antenna design specifications were fulfilled.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.409-413
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• 2008

In this paper, we introduce a platform of advanced multiple antenna system based on orthogonal frequency-division multiplexing (OFDM). The advanced multiple antennas have beamforming gain using array antenna. In array antenna systems, received signal has phase delay caused distance of each antennas, therefore it should compensate with optimum weight vector which calculated by Lagrange algorithm. To implement the presented above procedures using Digital Signal Processor (DSP), we should fixed-point design. The performance of implemented platform is verified through MATLAB$^{(R)}$ simulations with various signal environments.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.5
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• pp.568-573
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• 2019

Modern Radars are evolving into MFRs which can search multiple targets simultaneously and then track them. Additionally they should be able to avoid some external jamming signals. Applying to these MFRs, Antennas should be able to perform DBF including to not only real-time beam steering but also multi-beam forming simultaneously. And they can cancel the beam at the specific direction. In this paper, we describe the implementation of sub-array type antenna hardware which can be applying DBF. Also we propose the modified amplitude aperture distribution for suppressing the side lobe level and explain the sub-array receiver design with amplitude tapering. It consists in making the amplitude weighting in 2 steps. In order to compare two weighting cases, we investigate the G/T performance for the array antenna. At the conclusion, we make a comparative study for the dynamic range of every sub-array receiver and present the hardware implementation that is more advantageous for sub-array alignment and calibration in DBF.