• ETRI Journal
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• v.26 no.6
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• pp.605-614
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• 2004

In this paper, we investigate array calibration algorithms to derive a further improved version for correcting antenna array errors and RF transceiver errors in CDMA smart antenna systems. The structure of a multi-channel RF transceiver with a digital calibration apparatus and its calibration techniques are presented, where we propose a new RF receiver calibration scheme to minimize interference of the calibration signal on the user signals. The calibration signal is injected into a multi-channel receiver through a calibration signal injector whose array response vector is controlled in order to have a low correlation with the antenna response vector of the receive signals. We suggest a model-based antenna array calibration to remove the antenna array errors including mutual coupling errors or to predict the element patterns from the array manifold measured at a small number of angles. Computer simulations and experiment results are shown to verify the calibration algorithms.

• Journal of Korea Society of Digital Industry and Information Management
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• v.9 no.4
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• pp.51-57
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• 2013

Research on calibration of array antenna has become a hot spot in the area of signal processing and it is necessary to obtain the phase mismatch of each antenna channel. This paper presents a new calibration method for an array antenna system. In order to calibrate the phase mismatch of each antenna channel, we used primary synchronization signal (PSS) which exists in LTE downlink frame. Primary synchronization signal (PSS) is based on a Zadoff-Chu sequence which has a good correlation characteristic. By using correlation calculation, we can extract primary synchronization signal (PSS). After extracting primary synchronization signal (PSS), we use it to calibrate and reduce the phase errors of each antenna channel. In order to verify the new array antenna calibration algorithm which is proposed in this paper, we have simulated the proposed algorithm by using MATLAB. The array antenna system consists of two antenna elements. The phase mismatch of first antenna and second antenna is calculated accurately by proposed algorithm in the experiment test. Theory analysis and MATLAB simulation results are shown to verify the calibration algorithm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.2 s.117
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• pp.166-176
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• 2007

Measurement uncertainty assessment is very important in measurement and calibration. RRL provides antenna calibration services for EMI test. Reliability of EMI test depends on accurate antenna calibration. Antenna calibration results have to be accompanied with measurement uncertainty for its better reliability. In the late of 2005, CISPR issued the CISPR/A/644/C which describes the antenna calibration and measurement uncertainty. In this paper, on the basis of CISPR/A/644/C, we provide the measurement uncertainty values for dipole antenna calibration at the Calibration Test Site(CALTS) of Icheon. The antenna calibration method is 3-antenna height-scanning-averaging method, which measures the free-space antenna factor. We also considered all uncertainty sources that can affect measurement results during calibration.

• Journal of Korea Society of Digital Industry and Information Management
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• v.9 no.3
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• pp.59-65
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• 2013

This paper presents a novel calibration method for a base station system adopting an antenna array. The proposed technique utilizes Zadoff-Chu sequence, which is included in the LTE pilot signal periodically, in order to compute the phase characteristic of each antenna channel. As the Zadoff-Chu sequence exhibits an excellent autocorrelation characteristic, it is possible for the receiving base station to retrieve the Zadoff-Chu sequence transmitted from each mobile terminal. In addition, we can obtain the phase characteristic of each antenna channel, which is the ultimate goal of the calibration procedure. The proposed calibration algorithm has been implemented using an FPGA (Field Programmable Gate Array). We have applied the proposed algorithm to an array consisting of 2 antenna elements for simplicity. the phase value implied to the first and second antenna path is very accurately calculated from the proposed procedure. From the experimental test, the proposed method provides accurate calibration results.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1568-1572
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• 2004

This paper proposes a new online calibration algorithm for the array antenna system. As you know, the several previous calibration methods for the mutual coupling did not estimate but measure mutual coupling effect at the real or test-bed system directly. Therefore we suggest some idea to compensate the calibration errors due to mutual coupling effect and mismatch in cables and electronic modules without the off-line calibration. In this work, we can calibrate the array antenna system under the operation of the system using Independent Component Analysis(ICA). This is what is called an online calibration. As you know, the ICA method has permutation and scaling problems. However, we solve problems of the ICA method and apply it to the calibration of an array antenna. The method simultaneously estimates the DOA(Direction of Arrival) of the signals, and calibrates the array for that specific angle. The proposed algorithm is evaluated by computer simulation and its behavior is illustrated by a numerical example.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.2A
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• pp.139-146
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• 2009

This paper presents an average internal loop-back antenna calibration method for array antenna in TDD(Time Division Duplex) systems. The proposed method calibrates the amplitude and the phase of RF systems using into mal coupler and switches without aids of external calibration systems. The average calibration scheme of the proposed method also increases reliability of calibration performance. Computer simulation demonstrates that the proposed method corrects beamforming angles of DOA estimation algorithm and BER performance in transmit power allocation scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.1A
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• pp.18-30
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• 2004

In this paper, the calibration problem of an asynchronous CDMA-based antenna array is studied. A new iterative calibration algorithm for antenna array in the presence of frequency offset error is presented. The algorithm is applicable to a non-linear array and does not require a prior knowledge of the (direction of arrivals) DOAs of the signals of any user, and it only requires the code sequence of a reference user. The algorithm is based on the two step procedures, one for estimating both channel and frequency offset and the other for estimating the unknown array gain and phase. Consequently, estimates of the DOAs, the multi-path impulse response of the reference signal sources, and the carrier frequency offset as well as the calibration of antenna array are provided. The performance of the proposed algorithm is investigated by means of computer simulations and is verified by using field data measured through a custom-built W-CDMA test-bed.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2006.04a
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• pp.9-14
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• 2006

A determinated position with GPS (Global Positioning System) data processing is the position of the phase center of a GPS antenna. The phase center of a GPS antenna is. not a stable point and depends on the azimuth and elevation angles of GPS satellites. It is known that the phase center variations (PCV) of a GPS antenna are greater in the vertical than the horizontal directions. The PCV calibration models for a GPS. antenna has two approaches: relative and absolute. In this study. we compared the two calibration models using the six operational permanent GPS stations in South Korea and analysed the PCV of each station. In addition, we. tested two different kinds of GPS antennas and compared the results. The accuracy and precision of the relative calibration was worse than the absolute calibration.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.501-505
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• 2003

There are many antenna array errors. They will distort the array beam pattern and result in an increased sidelobe level. A calibration technique is proposed for correcting the antenna array errors such as mutual coupling and unequal feeder characteristics. These are modeled as a matrix representing the interaction between the radiating elements. The matrix is estimated from the measured array response vectors. The antenna array errors are corrected by modifying the beamforming weight vector. It is verified by the electromagnetic simulation and experiment that the proposed technique reduces the sidelobe level and increases the antenna gain.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.2
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• pp.199-205
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• 2004

There are many antenna array errors. They will distort the array beam pattern and result in an increased sidelobe level. A calibration technique is proposed for correcting the antenna array errors such as mutual coupling and unequal feeder characteristics. These are modeled as a matrix representing the interaction between the radiating elements. The matrix is estimated from the measured array response vectors. The antenna array errors are corrected by modifying the beamforming weight vector. It is verified by the electromagnetic simulation and experiment that the proposed technique reduces the sidelobe level and increases the antenna gain.