• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.3
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• pp.404-408
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• 2014

In this research we evaluate the excitation homogeneity and SAR of three different Tx arrays after B1+ Shimming in the human body at 3T. Through the simulations, we compared the field properties that are standard deviation and mean value of transverse magnetization for 1) strip line TEM array, 2) rectangular loop array, 3) combined array of strip line element and rectangular loop and shown the utilities of B1+ shimming in human body model. After B1+ shimming, it is evaluated four different types of SAR for body mesh through whole body simulation; those are average, maximum 1-cell, maximum 1-gram, and maximum 10-gram SAR. It appears that in this particular comparison an array based on strip line elements can produce better homogeneity and lower SAR than an array of rectangular loops or an array of combined elements (strip line and loop). While many factors are considered in designing coils for production, it is hoped that methods and results like these will be used in the future to guide decisions and maximize benefit.

• Journal of Ocean Engineering and Technology
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• v.28 no.5
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• pp.474-483
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• 2014

The majority of existing WECs (wave energy converters) are designed to achieve maximum power at a resonance condition. In the case of a single WEC, its size must be large enough for tuning, and it has high efficiency only within a limited frequency band. Recently, wave power extraction by deploying many small buoys in a compact array has been studied under the assumption that the buoy's size and separation distance are much smaller than the water depth, wave length, and size of the array. A boundary value problem involving the macro-scale boundary condition on the mean surface covered by an infinite strip of buoys is solved using the eigenfunction expansion method. The energy extraction efficiency (${\varepsilon}=1-R^2_f-T^2_r$), where $R_f$ and $T_r$ are the reflection and transmission coefficients for a strip array of buoys, is assessed for various combinations of packing ratio, strip width, and PTO damping coefficient.

• Journal of electromagnetic engineering and science
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• v.2 no.2
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• pp.87-92
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• 2002

A short-ended electromagnetically coupled coaxial dipole array antenna is investigated theoretically. The antenna has an advantage of structural simplicity. The integral equations are derived for the proposed structure by use of the Fourier transform and mode expansion, and the simultaneous linear equations are obtained. The slot electric field and strip current are obtained by solving the simultaneous linear equations. The effects of slot and strip numbers on the radiation efficiency, beamwidth and directivity gain of the antenna are presented.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.399-403
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• 2000

A new type of collinear antenna called short-ended coaxial slot-coupled strip array antenna is investigated theoretically. The antenna has an advantage of structural simplicity. The integral equations are derived for the proposed structure by use of the Fourier transform and mode expansion, and the simultaneous linear equations are obtained. The slot electric field and strip current are then obtained by solving the simultaneous linear equation. The effects of slot and strip number on the radiation efficienty, beamwidth and directivity gain are also presented.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.8
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• pp.1598-1603
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• 2003

A microstrip array antenna is designed and tested for satellite broadcasting receptions. The Sierpinski equilateral triangular patch and SSFIP(slot­strip­foam­inverted patch) structures are used. The Sierpinski geometry is composed of 3 equilateral triangular patch and is easy to generate a circular polarization by sequential rotation array techniques. This 1${\times}$3 Sierpinski equilateral triangular patch antenna is extended to 8${\times}$2 array antenna for satellite broadcasting receptions. The measurement results of the reflection coefficients and the radiation patterns of the manufactured array antenna show good agreements with the simulation results.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.49-52
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• 2003

A microstrip array antenna is designed and tested for satellite broadcasting receptions. The Sierpinski equilateral triangular patch and SSFIP(slot-strip-foam-inverted patch) structures are used. This 1$\times$3 Sierpinski equilateral triangular patch antenna is extended to 8$\times$2 array antenna for satellite broadcasting receptions. The measurement results of the reflection coefficients and the radiation patterns of the manufactured array antenna show good agreements with the simulation results.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.63-64
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• 2015

In this paper, a microstrip array antenna capacitively coupled to a microstrip line is studied. The array antenna consists of uniformly spaced rectangular microstrip patches arranged close to a feeding microstrip line on a grounded dielectric substrate. The effects of various parameters, such as strip width and length, distance between adjacent patches, gap between strip patches and microstrip feed line, on the antenna performance were examined. By properly adjusting geometrical parameters, the array suitable for a high gain antenna for use in a frequency band centered at 12.5 GHz was designed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.2
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• pp.196-203
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• 2015

In order to apply cylindrical periodic array to phased array antenna or frequency selective surface, efficient electromagnetic analysis is required. Finite periodic array is applied in real situation. But, generally, assumed that periodic structure is arranged infinitely, approximate electromagnetic characteristics can be obtained efficiently. But, difference of characteristics between real structure and approximate structure occurs because finite periodic array is approximated to infinite periodic array. Therefore, comparison and analysis of cylindrical infinite array and finite array are required. In this paper, cylindrical infinite periodic array are analyzed using cylindrical Floquet harmonics. Also, cylindrical finite periodic array is analyzed using method of moments (MoM) with thin wire approximation because periodic structures which are composed of strip with narrow width are analyzed. Transmission characteristics and surface currents of infinite and finite periodic structures are compared.

• Journal of Advanced Navigation Technology
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• v.27 no.4
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• pp.447-452
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• 2023

In this paper, gain enhancement of a double dipole quasi-Yagi antenna using a meanderline array structure was studied. A 4×1 meanderline array structure consisting of a meanderline conductor- shaped unit cell is located above the second dipole of the double dipole quasi-Yagi antenna. It was designed to have gain over 7 dBi in the frequency range between 1.70 and 2.70 GHz in order to compare the performance with the case using a conventional strip director. As a result of comparison, the average gain of the double dipole quasi-yagi antenna with the proposed meander line array structure was larger compared to the case with the conventional strip director. A double dipole quasi-Yagi antenna using the proposed meanderline array structure was fabricated on an FR4 substrate and its characteristics were compared with the simulation results. Experiment results show that the frequency band for a VSWR less than 2 was 1.55-2.82 GHz, and the frequency band for gain over 7 dBi was measured to be 1.54-2.83 GHz. The frequency bandwidth with gain over 7 dBi increased, and average gain also slightly increased, compared to the conventional case using a strip director.

• Journal of Advanced Navigation Technology
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• v.28 no.2
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• pp.232-237
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• 2024

In this paper, a broadband double dipole quasi-Yagi antenna using a 4×2 meander line array structure for maintaining 8 dBi gain was studied. The 4×2 meanderline array structure consists of a unit cell in the shape of a meanderline conductor, and it was placed above the second dipole antenna of the double dipole quasi-Yagi antenna. A double dipole quasi-Yagi antenna with generally used multiple strip directors was designed on an FR4 substrate with the same size, and the input reflection coefficient and gain characteristics were compared. Comparison results showed that the impedance frequency bandwidth increased by 6.3% compared to when using the multiple strip directors, the frequency bandwidth with a gain of 8 dBi or more increased by 10.1%, and average gain also slightly increased. The frequency band of the fabricated antenna for a voltage standing wave ratio less than 2 was 1.548-2.846 GHz(59.1%), and gain was measured to be more than 8 dBi in the 1.6-2.8 GHz band.