• Journal of electromagnetic engineering and science
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• v.5 no.2
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• pp.72-79
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• 2005

The leaky dispersion characteristics of a circular dielectric rod were investigated using Davidenko's method for several lower-order transverse magnetic(TM) modes. The normalized complex propagation constants were precisely determined and their tolerances below $10^{-10}$ compared with zero for both real and imaginary parts. It was also checked whether the normalized complex propagation constants obtained represented forward leaky waves. The leaky modes existing below the cutoff frequency of the guided mode were classified as a nonphysical mode, reactive mode, antenna mode, and spectral gap based on a precise determination of the complex propagation constants. Finally, the effects of the dielectric constant and radius of the dielectric rod on the leaky dispersion characteristics were also considered.

• KIEE International Transactions on Electrophysics and Applications
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• v.3C no.5
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• pp.199-206
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• 2003

Numerical solutions to complex characteristic equations are quite often required to solve electromagnetic wave problems. In general, two traditional complex root search algorithms, the Newton-Raphson method and the Muller method, are used to produce such solutions. However, when utilizing these two methods, the choice of the initial iteration value is very sensitive, otherwise, the iteration can fail to converge into a solution. Thus, as an alternative approach, where the selection of the initial iteration value is more relaxed and the computation speed is high, Davidenko's method is used to determine accurate complex propagation constants for leaky circular symmetric modes in circular dielectric rod waveguides. Based on a precise determination of the complex propagation constants, the leaky mode characteristics of several lower-order circular symmetric modes are then numerically analyzed. In addition, no modification of the characteristic equation is required for the application of Davidenko's method.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.356-360
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• 2002

Leaky modes on a circular dielectric rod are investigated from the precisely determined normalized complex propagation constants using Davidenko's complex root finding technique. Below the cutoff frequency of the guided mode, distinct frequency regions that have unique properties are observed, such as nonphysical region, antenna mode region, reactive mode region, and spectral gap region. The effects of tro design parameters, dielectric constants and the radius of the rod, to the leaky mode characteristics are also considered.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.367-370
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• 2005

In this paper, we made a Singly Fed patch which is the fittest at the feeding part. And we found out return loss and radiation pattern about dielectric rod array antenna which has six's passive element to shape FTEP(Flat-topped element pattern) after we analyzed the characters of singly dielectric rod antenna. We show the conclusion that has the optimum return loss and more flat radiation pattern.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.59-63
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• 2003

Modal properties of guided waves along circular dispersive double negative (DNG) index metamaterial rod waveguides are numerically investigated. Identical forms of dispersive dielectric and magnetic material constants are used for simplicity. For degenerated azimuthally symmetric mode, a multimode region, a single mode region, a band gap region and a forbidden region are found which cannot be observed in the case of the conventional dielectric rod waveguide. As the normalized frequency goes down, discrete guided modes are continuously generated, which is a reverse property of conventional dielectric rod waveguide. Also, there are high-frequency cutoffs, which have been generally examined in dispersive circular geometries such as a plasma column or a plasma Goubau line. In the single mode region, both the low- and high-frequency cutoffs are existed where the propagation constants are continued between the guided oscillating and surface modes.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.1
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• pp.1-7
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• 2003

Leaky modes on a circular dielectric rod are investigated from the precisely determined normalized complex propagation constants using Davidenko's complex root finding technique. Below the cutoff frequency of the guided mode, distinct frequency regions that have unique properties are observed, such as nonphysical region, antenna mode region, reactive mode region, and spectral gap region.

• Journal of Korea Society of Industrial Information Systems
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• v.8 no.1
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• pp.9-17
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• 2003

The finite-difference time-domain (FDTD) method is used to analyze circular waveguide transformer in order to match different two waveguides. 2-dimensional cylindrical FDTD algorithm is applied for rotationally symmetric. The transformer is inserted at a circular-to-circular waveguide junction and two type transformers are proposed. One is a partially dielectric filled circular waveguide type and the other is filled a tapered circular dielectric rod. The numerical results are derived for various structure parameters, such as transformer length. dielectric diameter and waveguide diameter.

• Journal of electromagnetic engineering and science
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• v.7 no.3
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• pp.129-133
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• 2007

In this paper, we present the development of an antenna specialized for the maritime collision avoidance system. This antenna is configured as the dielectric rod partially embedded in the metal cavity to reduce the overall size, simultaneously assuring the mechanical sturdiness against the challenging oceanic weather conditions. More importantly, the design has been carefully done to meet the requirements on the radiation pattern(with the slope < 5 dB/deg in the elevation(E-plane), circular in the azimuth) suitable to receiving the reflected signals from the other objects on the sea. To find the optimal design parameters, the genetic algorithm has been used to meet the goals of the desired return loss and pattern. This design methodology is validated by the good agreement between the calculation and measurement.

• 한국가시화정보학회:학술대회논문집
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• 2007.11a
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• pp.51-54
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• 2007

The induced-charge electroosmosis (ICEO) is a kind of electroosmotic flow which is generated by the electrical charge induced by an externally-applied electric field. That kind of electrokinetic phenomenon provides a nonmechanical technique to handle microscale flows and particles. In this work, we report that the ICEO-like flow is observed around two kinds of circular-cylindrical rod submerged in a dielectric liquid. The conductivity of the solution is varied by adding a surfactant. The flow field is visualized by the PIV method, and average flow speed shows a remarkable dependence on electrical input frequency. Interestingly, the characteristics of the flow are quite different from the conventional ICEO with respect to the flow direction and the locations of center of vortices.

• ETRI Journal
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• v.36 no.6
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• pp.889-893
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• 2014

This paper presents a high-performance dual-circularly polarized feed employing a dielectric-filled circular waveguide. Novel features are incorporated in the proposed feed, such as a dielectric rod radiator for high gain and good impedance matching; dual quarter-wave chokes for low axial ratio over wide angles and for low back radiation; an integrated septum polarizer; and two end-launch-type coaxial-to-waveguide transitions. The proposed feed shows excellent performance at 5.0 GHz to 5.2 GHz.