• The Transactions of the Korean Institute of Electrical Engineers P
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• v.61 no.1
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• pp.5-9
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• 2012

In this paper, multi folded dual monopole antenna for WLAN communication of dual bend is designed and fabricated. The proposed multi folded dual monopole antenna are consisted of two folded rectangle loops by microstrip fed that is modified dual monopole antenna. Therefore, the outside rectangle loop structure of the proposed antenna is extended a dual monopole. The characteristics of the proposed antenna is analyzed return loss and radiation patterns by the FDTD tools. As a result a bandwidth of proposed antenna has about 0.82GHz from 2.0 to 2.82[GHz] and 0.7GHz from 5.46 to 6.16[GHz]. It is used WLAN communications of 2[GHz] and 5[GHz].

• Progress in Superconductivity
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• v.1 no.1
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• pp.42-46
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• 1999

A high-temperature superconducting 1.78 GHz bandpass filter, designed for PCS applications, is presented. The structure consists of microstrip pseudo-lumped elements, which enables miniaturization of the filter. A 5-pole microstrip filter could be realized on a 37 mm $\times$ 9 mm $LaAlO_3$ substrate, using double-sided high-temperature superconducting $YBa_2Cu_3O{7-\delta}$ thin film. This filter showed 0.7 % fractional bandwidth, 0.3 dB insertion loss, and 12 dB return loss in the passband at 60 K.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.7
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• pp.1459-1467
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• 1997

The current on the thin planar structure as an element of the transversely fed electromagnetically coupled(EMC) microstrip dipole array antenna is obtained by using the integral forms of the finite difference time domain(FDTD) method. This method was applied to calculating the optimum current distribution (Doplh-Tchebyscheff distribution) of each dipole element on the feed line as a function of their offset positions for the narrow main beam width and the side beam level below -20 dB. The current on each dipole substitutes for the electric and magnetic current densities on the virtual surface of the FDTD calculation to express the far field intensity, the calculation time and the computer memeory can be reduced to about 80% and 1.3 Mbyte, respectively. The calculated radiation patterns are compared to the measured values and these are in good agreement.

• Journal of electromagnetic engineering and science
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• v.7 no.2
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• pp.96-101
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• 2007

A design of circular polarized(CP) microstrip antenna with a fenced ground is proposed and the equivalent circuit is derived. The antenna consists of a square radiating patch with a pair of truncated comers, a bottom ground and a fenced ground. From conducted experiments, a patch size reduction using the metal fence as large as 25% from the conventional patch structure, has been obtained. The input admittance of the extracted equivalent circuit is shown to agree with that of the measurement. And the design parameters and performance of the proposed antenna are examined by analyzing the fields and circuit behaviors.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1828-1830
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• 1998

In this paper, an analysis of microstrip-slotline transiton is performed using a 3D vector Finite Element Method(FEM). On the base of the analysis, power divider/combiner is designed. The optimal structure for equal power division in Ka band is also proposed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.4
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• pp.611-621
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• 2001

This paper presents a design methodology of bandpass filter by using defect modes in photonic bandgap (PBG) structures. PBG structures are realized with alternating section of microstrip line arranged in a periodical manner. A passband is created within the stopband of PBG structures with defect modes, which can be generated by changing the period of certain part of PBG structure. We also extract a simple equivalent circuit of a bandstop filter by using several LC sections.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.6
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• pp.363-644
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• 1997

This paper presents the design and fabrication of a shaped-beam array antenna which will be used for a PCS basestation using structure that is coupled to a microstrip line by an aperture on the interening ground plane. The shaped-beam pattern is obtained by an antenna synthesis method. An array antenna considering the mutual coupling between array elements patches) and a feeding network are designed by CAD tools. The feeding network is designed by using the Wilkinson power divider to obtain the optimized shaped-beam. The designed results are compared with the measured data.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.227-229
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• 2002

In this paper, we report on a microstrip line voltage controlled tunable bandpass filter. We used the characteristic the relative dielectric constant of thin film ferroelectrics depends on the applied dr voltage. we designed using Au/BSTO/MgO/Au structure. We cascaded many resonators for large furling range sustaining 1 GHz renter frequency, narrow band, low IL ($\leq$4 dB). We could design the BPF of which center frequency is 16 GHz, 1.9 GHz tuning range, the narrow bandwidth within 800 MHz, low insertion loss less than 3 dB by adjusting the gap of 3 cascaded resonators.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.04a
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• pp.1-4
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• 2004

In this paper we developed Composite-Smart-Structures(CSS) using sandwich structure composed of Glass/Epoxy laminates and Nomex honeycomb and microstrip antenna. Transmission/reflection theory shows that antenna performances can be improved due to multiple reflection by Glass/Epoxy facesheet, and honeycomb is used for air gap between antenna and facesheet. Stacked radiating patches are used for the wideband. Facesheet and honeycomb thicknesses are selected considering both wideband and high gain. Measured electrical performances show that CSS has wide bandwidth over $10\%$ and higher gain by 3.5dBi than initially designed antenna, and no doubt it has excellent mechanical performances by sandwich effect given by composite laminates and honeycomb core. The CSS concept can be extended to give a useful guide for manufacturers of structural body panels as well as antenna designers, promising innovative future communication technology.

• Journal of Magnetics
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• v.22 no.2
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• pp.275-280
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• 2017

A magnetic-field tunable 2.4 GHz microwave bandpass filter having insertion loss < -5dB on an FR4 substrate with the flaky magnetic material was designed and characterized. The tunability in the designed bandpass filter was achieved by adhering soft magnetic materials on top of the device. This soft magnetic material can be composed of ferromagnetic substance or ferrimagnetic substance. The performance of the designed bandpass filter under its influence is investigated. The frequency offset ratio changes over 30 %. There is over 20 % change in the center frequency towards the lower frequency region due to this application. These magnetic material layers achieved the center frequency shift and bandwidth extension without actually changing the original structure of the device.