• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.6
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• pp.43-55
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• 2013

In this paper, we propose a cylindrical active phased array antenna of Beam Steering Characteristics in the horizontal plane(H-plane) and vertical plane(E-Plane) on the cylinder form array structure. We design the bent dipole antenna of the cylindrical array structure adapted excellent mutual-coupling characteristics, designed and manufactured the cylindrical array antennas and power combiner/divider unit for power dividing and combining on the antenna. The radiating elements array spacing of Cylindrical array antenna were determined to avoid grating lobes at half power beam steering. Beam steering of the antenna was implemented with 6-bit phase shifter in the transceiver and have been designed based on the characteristics the antenna beam steering at -24 degrees to 24 degrees horizontal, vertical 0 degrees to 36 degrees beam steering. A cylindrical active phased array antenna that produced for verification the performance of the antenna are measured radiation characteristics in accordance with beam steering at L-Band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.12 s.115
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• pp.1189-1198
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• 2006

We analyze the radiated emission and mutual coupling problem from a single microstrip transmission line and double signal traces with various ground patterns. In this paper, it is shown that the reduction of the radiated emission from the signal traces can be accomplished by using the novel and compact patterns on the ground planes in a specific frequency band. The accuracy and validation of radiation mechanism from the transmission line on a novel ground plane are evaluated and explained by using a commercially available software and experiment, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.12
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• pp.1427-1434
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• 2008

Compact quadruple inverted-f antenna(QIFA) with circular polarization for GPS receiver is proposed. Radiation efficiency is decreased when 4-port antenna is smaller. A new matching method is proposed by considering both a return loss at one port and mutual coupling between ports to increase radiation efficiency. Experimental results show that the proposed QIFA has a 3-dB beamwidth of more than 120 degrees and a front-to-back ratio of more than 15 dB. Also, the QIFA has the peak gain of -2.5 dBic and the axial ratio under 0.5 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.6
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• pp.495-503
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• 2016

This paper proposes the design of multiband repeater antenna with fire-fighting band for in-building mobile communication. The proposed antenna is composed of a center monopole and 4 parasitic elements on a circular plate. In order to realize good reflection coefficients at the multiband, mutual coupling between 4 parasitic elements and center monopole antenna is considered. The important parameters such as distance between parasitic element and a center monopole, and each height of a center monopole and 4 parasitic elements are simulated to obtain good antenna characteristics at the multiband. The diameter of 4 parasitic elements and a center monopole was fixed to 10 mm for easy design and manufacturing. The measurement results of reflection coefficients, 2-D patterns and gain agreed well with their simulation ones.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.10
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• pp.1166-1172
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• 2012

In this paper, by using a commercial EM simulator, we could obtain the array manifold which are phase responses of an array antenna for the incident plane wave and then verified the effectiveness of methodology after comparing with the measurement. The result shows that the array manifold can be calculated including not only the phase response of the ideal point sources but also the influences of the mutual coupling between antennas and the installed platform. Also it can exclude the interference of strong broadcasting signal and the disturbance of the multipath in the calibration process. Finally, to predict the performances of direction finding systems, a novel method using both the EM simulation-based receiving signal and the sparsely sampled array manifold with the parabolic estimation is proposed. This method can be utilized in the various fields of direction-finding since it shows the superior predictive performance even in low SNR conditions.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.1
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• pp.24-29
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• 2015

In this paper, we propose a method of isolation improvement for broadband antennas using a high-permeability substrate. The substrate is applied for a planar monopole antenna based on near-field analysis to maintain radiation characteristics at its operating frequency while improving isolation by minimizing mutual coupling with nearby antennas at other frequency bands. To verify isolation improvement, we compare performance variations of $S_{21}$ according to the existence of the substrate using the proposed antenna and a reference antenna whose operating frequency is 2 GHz. As a result, the radiation characteristics are maintained, and $S_{21}$ performance is improved by more than 5~10 dB in the frequency band of greater than 2 GHz, which demonstrates the isolation can be improved by using the high-permeability substrate.

• Journal of Digital Contents Society
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• v.6 no.2
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• pp.101-106
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• 2005

In this paper, performance evaluation of mobile access layer for multiple-input multiple-output (MIMO) MultiCarrier(MC)/CDMA 16 QAM system is considered to mitigate multiple access interference and enhance system channel capacity in Rayleigh wireless fading channel. Traditionally, multi-path is viewed as an undesirable feature of wireless communications. Therefore, diversity and adaptive array schemes are proposed to mitigate its effects. Recently, to increase the spectrum efficiency and the link reliability, MIMO schemes is devised to exploit multi-path in a scattering wireless channel. In particular, the channel capacity of MIMO-MC/CDMA 16 QAM system is evaluated according to Eb/No, Mc, p. From the results, in order to improve the channel capacity, the signals at various elements must be uncorrelated. And if the paths are correlated due to inappropriate spacing or mutual coupling effects, the channel capacity of MIMO-MC/CDMA 16 QAM system becomes substantially smaller.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.939-940
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• 2015

In this paper, a design method for a quasi-Yagi antenna (QYA) suitable for UHF band is studied. Due to the mutual coupling between a coplanar strip (CPS)-fed planar dipole and a conducting strip director placed close to the dipole, the dipole obtains broadband characteristics. A ground reflector improves gain in the lower frequency band, and the antenna size might be reduced by employing a bent reflector. The balun between the CPS line and the microstrip(MS) line is constructed by connecting the end of MS line and the CPS line through a shorting pin. In addition, a ring-type conductor connects the CPS line and reflector. The effects of various geometrical parameters and balun on the antenna characteristics are examined. An antenna, as an design example for the proposed antenna, is designed for the operation in the frequency band of 470-806 MHz for terrestrial DTV.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.10
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• pp.17-24
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• 2000

An area efficient and symmetric dual-level spiral inductor structure is proposed and evaluated in comparison with the conventional single-level spiral inductors. Contrary to the dual-level inductor mutual coupling coefficient of the upper-and lower-level inductors of the dual-level inductor increases with the increases in the number of turns. Because of this, for the same silicon area, the inductances of the dual-level incuctors are 2.5-4 times higher than that of the single-level inductor. Furthermore, the dual-level showed better quality factor that the single-level inductors for the same inductance. It is the intention of this paper to demonstrate that the dual-level can be more useful for the RF integrated circuits than the conventional single-level spiral inductors form the aspects of area efficiency and quality factor. The proposed dual-level inductors are designed and confirmed to be perfectly symmetric, and can also be used as a high-frequency choke.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.2
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• pp.19-28
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• 2010

Generally, combustion instability is generated by the mutual coupling between the heat release and the acoustic pressure in the combustor. On the occasion, the acoustic pressure generates the oscillation of the mass flow rate of propellant injected from injector, and this oscillation again affects combustion in the combustor. So, the dynamic characteristics of the injector have been studied to control combustion instability using injector itself in Russia from 1970's. In order to study injector dynamics, a mechanical pulsator for forced pressure pulsation is produced and the method to quantify the mass flow rate of the propellant that is oscillating at the exit of the injector is developed. With the pulsator and the method, pulsating values of the mass flow rate, pressure, liquid film thickness, and axial velocity generated at the exit of the simplex swirl injector are measured in real time. And phase-amplitude characteristics of each parameter are analyzed using these pulsating values acquired at the exit of the simplex swirl injector.