• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.419-422
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• 2007

This paper, designed UWB elliptical slot antenna and analysis based on the distribution of the electromagnetic fields pattern and resonant mode of designed antenna is presented. Designed antenna is fabricated on FR4 substrate with thickness of 1.524mm and relative dielectric constant 4.4. The measured bandwidth of $3.6GHz{\sim}20GHz$ for VSWR<2. Through the field pattern and resonant mode analysis that the slot antenna operates on a series of the multi-pole radiation based on TE modes matched to system impedance. And the perfect magnetic wall is along the axis of symmetry on the y-z plane. This result gives us an easier method to design the similar antennas, which is the impedance matching to the system impedance after once constructing a proper structure with a series of multi-mode resonances.

• Journal of the Korea Society for Simulation
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• v.14 no.4
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• pp.69-76
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• 2005

To investigate the characteristics of the sound-pipe on the top of King Song-Dok bell, using computer simulation, the throat impedance was evaluated for the straight pipe and conical pipes with varying taper angles. When sound propagates in a rigid walled, unflanged circular pipe with wavelength larger than radius, the acoustic motion is planar, much as in a bar. The incident sound waves are reflected at the end of pipe and some of them are transmitted. The reflection coefficient and radiation impedance of the sound-pipe of King Song-Dok bell were calculated, and the results demonstrated that the high frequency sound is radiated through the sound-pipe. It behaves like a frequency filter.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.511-514
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• 2003

In this paper, describes the design of PIFA for PDA which has parasitic patch to expand the impedance bandwidth and miniaturization technique to consider the radiation pattern. To expand the impedance bandwidth, generated resonant frequency of parasitic patch is different from that of main patch. To miniaturize the physical dimension, using the folded edge and rectangular slot. The obtained impedance bandwidth is 9.4% ($2.29GHz{\sim}2.515GHz$) at VSWR${\leqq}$2 and antenna gain is 2dBi within the operating frequency.

• ETRI Journal
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• v.30 no.4
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• pp.597-599
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• 2008

This letter presents the design of a small and low-profile RFID tag antenna in the UHF band that can be mounted on metallic objects. The designed tag antenna, which uses a ceramic material as a substrate, consists of a radiating patch and a microstrip line with two shorting pins for a proximity-coupled feeding structure. Using this structure, impedance matching can be simply obtained between the antenna and tag chip without a matching network. The fractional impedance bandwidth for $S_{11}$ <3 dB and radiation efficiency are about 1.4% and 56% at 911 MHz, respectively. The read range is approximately from 5 m to 6 m when the tag antenna is mounted on a metallic surface.

• ETRI Journal
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• v.40 no.3
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• pp.303-308
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• 2018

This paper proposes a simple yet accurate method for estimating the antenna correlation coefficient (ACC) of a high-order multiple-input multiple-output (MIMO) antenna. The conventional method employed to obtain the ACC from three-dimensional radiation patterns is costly and difficult to measure. An alternate method is to use the S-parameters, which can be easily measured using a network analyzer. However, this method assumes that the antennas are highly efficient, and it is therefore not suitable for lossy MIMO antenna arrays. To overcome this limitation, we define and utilize the non-coupled radiation efficiency in the S-parameter-based ACC formula. The accuracy of the proposed method is verified by the simulation results of a 4-port highly coupled lossy MIMO array. Further, the proposed method can be applied to N-port arrays by expanding the calculation matrix.

• Journal of electromagnetic engineering and science
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• v.5 no.2
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• pp.97-103
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• 2005

This paper describes the measured results of sonobuoy transmitting antenna system for anti-submarine warfare (ASW). Since radiation pattern and power density depend on impedance matching between transmitting RF part and antenna with termination resistance, design of matching circuit is very important for sonobuoy system performance. Matching circuit is designed by Smith chart using control of L and C. In standing wave ratio(SWR) measurement using Network Analyzer, SWR of antenna with matching circuit observed 1.5 below at the assigned VHF band. It shows very excellent performance comparison with conversional product that is used for the same object. The measured vertical and horizontal radiation patterns are also shown the satisfaction of military specifications. A drop out of sonobuoy system on the sea is happened when angle of elevation direction is over 10 degrees, and it is conformed that it takes less than I second return to original signal level. The required electric power density is $83\;mW/m^2$ in the military specification, and measured electric power density is observed over average $110\;mW/m^2$ at all frequency bands.

• Journal of electromagnetic engineering and science
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• v.10 no.3
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• pp.171-174
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• 2010

In the paper, a printed dual-dipole array antenna is presented. A 4-way planar SIW power divider is adopted for feeding the array antenna. The dual-dipole is adopted as radiation elements which greatly improves the impedance band. The measured bandwidth larger than 31 % for VSWR$\leq$1.5 operating near 14 GHz is achieved and in agreement with the simulated results. The radiation E-plane and H-plane radiation pattern is presented in the paper. The radiation gain is also presented in the paper.

• Journal of KSNVE
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• v.6 no.6
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• pp.717-726
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• 1996

In this report, the underwater sound radiation from finite cylindrical shell with stiffeners which is the basic configuration of submerged vehicle is studied analytically and experimentally. The shell vibrations are obtained by using the shell theory of Sanders-Koitter. The stiffeners and modeled for I-type and the stiffness matrices are obtained by using beam model. In the analytical stuides, the vibrations of cylindrical shell are expressed by using cosine series expansions to consider the arbitrary end boundary conditions. It is agree to the theoretical and experimental results well.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.7
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• pp.1-8
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• 1998

In this paper, the radiation characteristics of a bar-type tranceiver are analyzed by using FDTD method and the effectiveness of the analysis method is verified by comparing the calculated data with experimental data. The effects of human head and hand on the radiation characteristics of fold-type transceiver are analyzed. In order to observe the effects of human head and hand on the input impedance and far-field radiation pattern, a fold-type transceiver with .lambda./4 monopole antenna wrapped by human hand operating in the proximity of hea dis modeled an analyzed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.4
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• pp.261-268
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• 2017

In this paper, we propose an FSSH(Folded Slot Spherical Helix) magnetic dipole antenna with a form factor easy to build and study its radiation properties. The number of folded arms, the gap between them and the metal thickness are tuned to achieve relatively simple structure to realize whereas maintaining high radiation efficiency at an electrically small size. The proposed design shows wide radiation efficiency bandwidth and it is confirmed by circuit simulation that the non-Foster impedance matching techniques could be utilized for its practical use. The prototype of the proposed antenna is built with the aid of an SLS(Selective Laser Sintering) 3D printing technology. The measured result shows lower Q impedance characteristic due to high resistive loss of the copper tape joints.