• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.9
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• pp.841-848
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• 2016

In this paper, a microstrip-fed dual-band monopole antenna with DGS(: Defected Ground System) for WLAN(: Wireless Local Area Networks) applications was designed, fabricated and measured. The proposed antenna is based on a microstrip-fed structure, and composed of two strip lines and DGS structure and then designed in order to get dual band characteristics. We used the simulator, Ansoft's High Frequency Structure Simulator(: HFSS) and carried out simulation about parameters W2, L10, W3, and DGS to get the optimized parameters. The proposed antenna is made of $21.0{\times}36.0{\times}1.6mm3$ and is fabricated on the permittivity 4.4 FR-4 substrate. The experiment results are shown that the proposed antenna obtained the -10 dB impedance bandwidth 700 MHz(2.10~2.80 GHz) and 1,780 MHz(5.02~6.80 GHz) covering the WLAN bands. Also, the measured gain and radiation patterns characteristics of the proposed antenna are presented at required dual-band(2.4GHz band/5.0GHz band), respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.9
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• pp.1996-2002
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• 2013

In this paper, a design method for a compact broadband planar monopole antenna fed by a coplanar waveguide (CPW) is studied. The proposed broadband monopole is optimized for terrestrial digital television (DTV) reception. In order to achieve broadband characteristics, the monopole and ground conductor are gradually tapered. By loading slit pairs on both monopole and ground plane, the proposed antenna is miniaturized. The monopole is fed by a CPW with 75-ohm characteristic impedance on an FR4 substrate and its size is $100mm{\times}200mm$. The optimized monopole antenna for DTV band (470-806 MHz) is fabricated on an FR4 substrate and tested experimentally to verify the results of this study.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.2
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• pp.303-312
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• 2009

In this paper, we design and fabricate a disk sector antenna fed by CPW fur UWB communications. Also, we insert a rectangular slit on the arc-edge of the disk sector antenna. Then, the antenna has the directivity of E-면. In order to design the antenna, the input impedance is matched with the feed line of $50{\Omega}$ as varying the physical antenna parameters, which are the radius, the flare angle of disk sector, the length of ground, and the length of ground comer near by feed tine. Dimension of the antenna designed for UWB communication is $72mm{\times}26mm$ and bandwidth through computer simulation is $3{\sim}13GHz$. From the measured results, the bandwidth is $1.98{\sim}11GHz$. Return loss and gain of the fabricated antenna are -50.38dB, 1.34dBi at 3.5GHz, -12.27dB, 3.35dBi at 5.5GHz, -23.2dB, 3.8dBi at 8GHz and -16.17dB, 5.2dBi at 10GHz, respectively.

• Journal of Advanced Navigation Technology
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• v.24 no.2
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• pp.142-147
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• 2020

In the present study, we proposed newly a CPW-fed miniaturized folded-slot antenna with open ended slot for WCDMA (1.92 ~ 2.17 GHz) band. Open-ended slots and asymmetric ground plane are used for a miniaturization of the antenna, and the proposed antenna was designed and fabricated on a FR-4 substrate with dielectric constant 4.3, thickness of 1.6 mm, and size of 35×70 ㎟. The measured impedance bandwidths (|S₁₁| ≤ -10 dB) of fabricated antenna is about 400 MHz (1.86 ~ 2.26 GHz), which sufficiently satisfied interested band. Furthermore, the gain of antenna is 2 dBi and this antenna shows a similar radiation patterns of the dipole antenna. Therefore, it is expected to be used usefully in wireless and mobile communication device.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.63-64
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• 2018

In this study, a design method for a circular polarization patch antenna operating at a frequency 1.5 GHz~1.7 GHz was studied. To obtain the wide bandwidth and high gain, air substrate between patch and ground plane was applied. The impedance bandwidth is improved by adjusting the sizes of patch, the distance between main patch and ground plate, the length of internal slots, the position of feeding point, the length of external stub, etc. The antenna is designed and simulated for an operation in the frequency range of 1.5GHz~1.7GHz band. The results show that antenna characteristics such as return loss, gain, axial ratio, radiation patterns are appropriate for the satellite navigation system.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.7
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• pp.37-45
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• 2002

In this paper, the microwave characteristics of traveling-wave electroabsorption coplanar waveguide modulator have been analyzed and optimized precisely by using the 3-dimensional finite-difference time-domain method (FDTD). Microwave characteristics are affected by the thickness of intrinsic layer, the width of meas, and the distance between signal electrode and ground electrode on traveling-wave type structure. In case that intrinsic layers are composed of InAsP/InGaP (1.3Q), the optimized distance between signal electrode and ground electrode, the optimized intrinsic region thickness and the width of waveguide are founded to be $3{\mu}m,\;039{\mu}m\;and\;2{\mu}m$, respectively, to minimize microwave loss and to obtain velocity and impedance matched structure. By using the FDTD, we could design the traveling-wave electroabsorption modulator more precisely.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.8
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• pp.899-905
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• 2008

In this paper, we propose a dual-spiral line loaded monopole antenna having a vertical ground plane for quadband applications. The antenna occupies a volume of $38{\times}12{\times}7\;mm^3$ with a $40{\times}92\;mm^2$ ground plane. The measured impedance bandwidths of the antenna based on $VSWR{\le}2$ are approximately of 11.7 % and 24.8 % in the first and second frequency band, respectively. The operating frequency can simultaneously cover Cellular($0.824{\sim}0.894\;GHz$), PCS($1.750{\sim}1.870\;MHz$), UMTS($1.920{\sim}2.170\;MHz$), and IMT-2000($1.885{\sim}2.200\;GHz$) bands. The maximum gains of the antenna are -0.99 dBi, 4.07 dBi, 2.72 dBi, and 4.33 dBi at the center frequencies of the Cellular, PCS, UMTS, and IMT-2000 bands, respectively. Good radiation patterns are experimentally obtained.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.5
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• pp.516-521
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• 2011

In this paper, an inverted-triangle patch UWB antenna with an uneven ground planes and an inverted T-slot for 5 GHz WLAN band rejection is presented. The operating bandwidth of the proposed antenna fed with the CPW line is expanded from 3.1 GHz to 10.6 GHz for about -10 dB return loss using three angular parameters correlated to the main patch and the ground plane. The fabricated antenna on Taconic RF-60A substrate with 6.16 relative dielectric constant and 0.64 mm thickness has a main antenna patch size of 36 mm${\times}$19.5 mm. The measured results show return losses of about -10 dB and nearly omni-directional radiation patterns. The proposed UWB antenna has advantages of easily adjustable impedance characteristics by the three angular parameters and easily accomplishable band rejection characteristics by the inverted T-slot.

• Journal of Biomedical Engineering Research
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• v.20 no.2
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• pp.205-212
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• 1999

When we want to observe and record a patient's EEG in an operating room, the operation of electrosurgical unit(ESU) causes undesirable artifacts with high frequency and high voltage. These artifacts make the amplifiers of the conventional EEG system saturated and prevent the system from measuring the EEG signal. This paper describes a high-performance bipolar EEG amplifier for a CSA (compressed spectral array ) system with reduced ESU artifacts. The designed EEG amplifier uses a balanced filter to reduce the ESU artifacts, and isolates the power supply and the signal source of the preamplifier from the ground to cut off the current from the ESU to the amplifier ground. To cancel the common mode noise in high frequency, a high CMRR(common mode rejection ratio) diffferential amplifier is used. Since the developed bipolar EEG amplifier shows high gain, low noise, high CMRR, high input impedance, and low thermal drift, it is possible to observe and record more clean EEG signals in spite of ESU operation. Therefore the amplifier may be applicable to a high-fidelity CSA system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.3 s.118
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• pp.305-314
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• 2007

In this paper, we suggested a CPW-fed UWB antenna with uni-planar sectoral structure. The area where radiation device face ground is designed to have the shape of tapered slot based on exponential function. We modified a rectangular bow-tie dipole structure antenna and thus formed a multi-resonant mode. From this, we expanded the impedance bandwidth and made a feature satisfying VSWR of less than 2 between $3.1\sim10.6GHz$. The test result showed that the return loss less than -10 dB was met in the full-band UWB system and maximum gain of $0.9\sim3.1dB$ was made with the half-power beamwidth of $40.1\sim89.9^{\circ}$ on XY plane(Theta, $Phi=90^{\circ}$) and the full band. By using CPW-fed structure with no ground on the back of the substrate, the suggested antenna is easy to design and its miniaturization is also possible.