• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.1
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• pp.37-44
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• 2009

In this paper, a TRS band(Trunked Radio System: $806{\sim}866\;MHz$) array antenna has a good front-to-back ratio characteristics for the mobile communication base station is proposed. The proposed array antenna is composed of the $5{\times}3$ radiated elements which are the microstrip dipole antennas with the cavity-backed reflector. For the validity of the proposed antenna, the $5{\times}3$ array antenna is designed, fabricated, and its radiation characteristics are measured. As a result of measurements, the antenna gain is over 13.3 dBi and the front-to-back ratio is over 40 dB at the useable frequency band. We confirm that the designed antenna can be used as the mobile communication base station antenna with the excellent back lobe characteristics.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.3
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• pp.224-228
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• 2015

In this paper, we study the method for desired signals estimation that array antennas are received signals. We apply sub spatial method of direction of arrival algorithm and adaptive array antennas in order to remove interference and noise signal of received antenna signals. Array response vector of adaptive array antenna is probability, it is correctly estimation of direction of arrival of targets to update weight signal. Desired signals are estimated updating covariance matrix after moving interference and noise signals among received signals. We estimate signals using eigen decomposition and eigen value, high resolution direction of arrival estimation algorithm is devided signal sub spatial and noise sub spatial. Though simulation, we analyze to compare proposed method with general method.

• Journal of The Korean Astronomical Society
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• v.54 no.6
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• pp.171-182
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• 2021

The lack of short baselines, referred to as the short-spacing problem (SSP), is a well-known limitation of the performance of radio interferometers, causing a reduction of the flux detected from source structure on large angular scales. The very large number of antennas operated in the Atacama Large Millimeter/sub-millimeter Array (ALMA) generates situations for which the impact of the SSP takes a complex form, not simply measurable by a single number, such as the maximal recoverable scale. In particular, extended antenna configurations, complemented by a small group of closeby antennas at the centre of the array, may result in a double-humped baseline distribution with a significant gap between the two groups. In such cases one should adopt as the effective maximal recoverable scale the one associated with the extended array and use only the central array to recover missing flux, as one would do with single dish or ACA (Atacama Compact Array) observations. The impact of the missing baselines can be very important and may easily be underestimated, or even overlooked. The present study uses ALMA archival data of the ²⁹SiO(8-7) line emission of the AGB star W Hydrae for a demonstration. A critical discussion of the reliability of the observations away from the star is presented together with comments of a broader scope. Properties of the circumstellar envelope of W Hya within ~15 au from the star, many of which are not mentioned in the published literature, are briefly described and compared with R Doradus, an AGB star having properties very similar to W Hya.

• Journal of IKEEE
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• v.27 no.4
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• pp.624-629
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• 2023

Estimation of signal parameters via rotational invariance techniques (ESPRIT) is an algorithm that estimates the angle of a signal arriving at an array antenna using the shift invariance property of an array antenna. ESPRIT offers the good trade-off between performance and complexity. However, the ESPRIT algorithm still requires high-complexity operations such as covariance matrix and eigenvalue decomposition, so implementation with a hardware processor is essential to estimate the angle of arrival in real time. In addition, ESPRIT processors should have high performance. The performance is related to the number of antennas, and the number of antennas required for each application are different. Therefore, we proposed an ESPRIT processor that provides 2 to 8 variable antenna configurations to meet the performance and complexity requirements according to the applied field. The proposed ESPRIT processor was designed using the Verilog-HDL and implemented on a field programmable gate array (FPGA).

• Journal of Positioning, Navigation, and Timing
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• v.5 no.1
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• pp.37-45
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• 2016

In this paper, design and implementation issues for a network-oriented RF emitter localization system with array antenna are discussed. For hardware, the problem of array mismatch and RF/IF channel mismatch are introduced and the calibration schemes for solving those problems are also provided. For software, it is explained how to overcome the drawback of conventional MUltiple Signal Identification and Classification (MUSIC) algorithm in a point of identifying the number of received signals and problems such as Data Association Problem and Ghost Node Problem in regard to multiple emitter localization are presented with some approaches for getting around those problems. Finally, for implementation, a criterion for arranging each of sensors and a requirement for alignment of array antenna' orientation are also given.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2000.11a
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• pp.419-427
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• 2000

The 4 by 4 microstrip phased array antenna designed and radiation characteristics are studied. The design frequency was chosen to be 5.8GHz. Chebyshev ratio was achieved by unequal power divider and Wilkinson power divider. The ratio of current at each port is 1 : 2.6 : 2.6 : 1 and then side lobe level is less than -30 dB. It is shown that the radiation beam direction can be changed up to 30。 by control the phase at each port. The result can be used to design electrically controllable microwave scanning antennas.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2001.02a
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• pp.142-144
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• 2001

We designed superconducting four-element patch array antenna which has single-feed circularly polarization and a resonance frequency of 11.85 GHz for DBS receiving system. Antennas have been fabricated from both gold conductor and $YBa_{2}$$Cu_{3}$$O_{7-x}$(YBCO) superconductor (thin films) for comparison. Simulated and measured results, and analysis on resonant frequency(fr), return loss, and bandwidth are presented.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.2
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• pp.24-32
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• 1992

The impedance matching properties of infinite planar arrays of rectangular waveguides with dielectric plug loading and sheath covering are studied here. The effects of several involved parameters on the impedance matching of the phased array antenna are investigated by calculating the reflection coefficients numerically. The improvement of impedance matching and the appearance of forced surface wave resonances are also discussed.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.318-319
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• 2003

이동통신 시스템에서 데이터, 음성, 영상신호를 효율적으로 전송하기 위해 위상 배열 안테나(Phased-Array Antenna： PAA)에 관한 연구가 최근 국내외적으로 활발히 진행되고 있다. 광통신 기술을 이용한 PAA용 실시간 지연선로 (True Time-Delay： TTD)는 넓은 대역폭, 저 손실, 전자파 간섭에 무관, 소형화, 특히 ‘beam squintr´ 현상이 없는 장점이 있기 때문에 각광을 받고 있다. 특히, 신호의 간섭을 줄이기 위해 안테나 방사 패턴의 부엽 (side lobe)의 크기를 감소시킬 수 있는 안테나 설계기술이 필요하다. (중략)

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.12-13
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• 2008

In this paper, we propose a performance evaluation method for MIMO antennas through channel sounding. From measurement data, the complex channel gain, delay, angle of arrival, and angle of departure of each multipath are estimated. Using these estimates, the MIMO channel impulse response adopting various types of antennas are constructed by replacing the array response vectors, considering antenna patterns and correlation among antenna elements. Comparisons are made in terms of the metrics computed from the impulse responses.