• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.1
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• pp.127-134
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• 2022

A modified folded monopole slot antenna for 3G WCDMA (1.91 ~ 2.17 GHz), 4G LTE (2.17 ~ 2.67 GHz), 3.5 GHz 5G (3.42 ~ 3.7 GHz) and Wi-Fi dual band (2.4 ~ 2.484 GHz / 5.15 ~ 5.825 GHz) was proposed for the first time. The proposed antenna is designed and fabricated on a FR-4 substrate with dielectric constant 4.3, thickness of 1.6 mm, and size of 35 × 60 mm². The measured impedance bandwidth of the proposed antenna is 2910 MHz(1.84 ~ 4.75 GHz) and 930 MHz(5.11 ~ 6.04 GHz), antenna gain in each frequency band is from 1.811 to 3.450 dBi. In particular, it was possible to obtain a commercially suitable omni-directional radiation pattern in all frequency bands of interest.

• Journal of Advanced Navigation Technology
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• v.20 no.5
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• pp.490-495
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• 2016

In the present study, a microstrip-fed monopole antenna is proposed for wireless local area network (WLAN) operations which cover dual band of 2.4 GHz (2.4 ~ 2.484 GHz) and 5 GHz (5.15 ~ 5.825 GHz). In order to obtain its compact structure and good omnidirectional radiation patterns, a modified inverted L-shaped slot separated from ground for impedance matching in 5 GHz band is etched on 2.4 GHz printed monopole antenna. The proposed antenna is designed and fabricated on a FR4 substrate with dielectric constant 4.3, thickness of 1.6 mm, and size of $30{\times}45mm^2$. The measured impedance bandwidths (${\mid}S_{11}{\mid}{\leq}-10dB$) of fabricated antenna are 270 MHz (2.22 ~ 2.48 GHz) in 2.4 GHz band and 890 MHz (5.08 ~ 5.97 GHz) in 5 GHz band respectively. In particular, high gain of more than about 4 dBi and good omnidirectional radiation patterns have been observed over the entire frequency band of interest.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.869-872
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• 2005

This paper presents a new switchable dual mode VCO(Voltage-Controlled Oscillator). The VCO is efficient in dual mode operation and has self-bias adjustment based on the operation frequencies of 2.4 GHz and 5 GHz. The switching is done using MOS transistors and tuning is done using MOS varactors. It is implemented using TSMC 0.18${\mu}$m CMOS technology. It is powered by 1.8V supply. The measured results showed that the overall tuning range is approximately 13% at 5 GHz and 8% at 2.4 GHz. The measured phase noise is approximately -102 dBc/Hz at 1 MHz offset for 5 GHz and -89 dBc/Hz at 600kHz offset for 2.4 GHz. The VCO showed tail currents of 2mA in 5GHz mode and 2.5mA in 2.4GHz mode from a 1.8 V supply, respectively.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.8
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• pp.42-50
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• 2007

This paper presents design methods for dual-frequency(2.4/5.8GHz) active receiving antennas. The proposed active receiving antennas are designed to interconnect the output port of a wideband antenna to the input port of an active device of High Electron Mobility Transistor directly and to receive RF signals of 2.4GHz and 5.2GHz simultaneously where the impedance matching conditions are optimized by adjusting the length of $1/20{\lambda}_0$(@5.8GHz) CPW transmission line in the planar antenna The bandwidth of implemented dual-frequency active receiving antennas is measured in the range of 2.0GHz to 3.1GHz and 5.25GHz to 5.9GHz. Gains are measured of 17.0dB at 2.4GHz and 15.0dB at 5.2GHz. The measured noise figure is 1.5dB at operating frequencies.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.1
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• pp.137-146
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• 2009

We present a micromechanical digital-to-analog (DA) variable capacitor using a parallel digital actuator array, capable of accomplishing high-Q tuning. The present DA variable capacitor uses a parallel interconnection of digital actuators, thus achieving a low resistive structure. Based on the criteria for capacitance range ($0.348{\sim}1.932$ pF) and the actuation voltage (25 V), the present parallel DA variable capacitor is estimated to have a quality factor 2.0 times higher than the previous serial-parallel DA variable capacitor. In the experimental study, the parallel DA variable capacitor changes the total capacitance from 2.268 to 3.973 pF (0.5 GHz), 2.384 to 4.197 pF (1.0 GHz), and 2.773 to 4.826 pF (2.5 GHz), thus achieving tuning ratios of 75.2%, 76.1%, and 74.0%, respectively. The capacitance precisions are measured to be $6.16{\pm}4.24$ fF (0.5 GHz), $7.42{\pm}5.48$ fF (1.0 GHz), and $9.56{\pm}5.63$ fF (2.5 GHz). The parallel DA variable capacitor shows the total resistance of $2.97{\pm}0.29\;{\Omega}$ (0.5 GHz), $3.01{\pm}0.42\;{\Omega}$ (1.0 GHz), and $4.32{\pm}0.66\;{\Omega}$ (2.5 GHz), resulting in high quality factors which are measured to be $33.7{\pm}7.8$ (0.5 GHz), $18.5{\pm}4.9$ (1.0 GHz), and $4.3{\pm}1.4$ (2.5 GHz) for large capacitance values ($2.268{\sim}4.826$ pF). We experimentally verify the high-Q tuning capability of the present parallel DA variable capacitor, while achieving high-precision capacitance adjustments.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.5
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• pp.944-949
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• 2015

This study proposed a patch antenna with a MIMO structure which is applicable for wireless communication equipment by combining a single patch antenna with a multi port. The proposed MIMO patch antenna was designed through the TRF-45 substrate with a relative permittivity of 4.5, loss tangent equal to 0.0035 and dielectric high of 1.6 mm, and the center frequency of the antenna was 2.45 GHz in the ISM (Industrial Scientific and Medical) band. The proposed MIMO patch antenna had a 500 MHz bandwidth from 2.16 ~ 2.66 GHz and 24.1% fractional bandwidth. The return loss and VSWR were -62.05 dB, 1.01 at the ISM bandwidth of 2.45 GHz. The Wibro band of 2.3 GHz was -17.43 dB, 1.33, the WiFi band of 2.4 GHz was -31.89 dB, 1.05, and the WiMax band of 2.5 GHz was -36.47 dB, 1.03. The radiation patterns included in the bandwidth were directional, and the WiBro band of 2.3 GHzhad a gain of 4.22 dBi, the WiFi band of 2.4 GHz had a gain of 4.12 dBi, the ISM band of 2.45 GHz had a gain of 4.06dBi, and the WiMax band of 2.5 GHz had a gain of 3.9 6dBi.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.6
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• pp.740-747
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• 2019

In this paper, an antenna applicable to WLAN and WiMAX frequency bands is designed, fabricated, and measured. The proposed antenna is designed to have two branch strip line in the patch plane and a rectangular slit in the ground plane based on microstrip feeding for triple band characteristics and added a vertical strip in the ground plane to enhance impedance bandwidth characteristics. The proposed antenna is designed on a substrate with a relative permittivity of 4.4, a thickness of 1.0 mm, and has a size of $18.0mm(W1){\times}37.3mm$ (L4+L5+L7). From the fabricated and measured results, impedance bandwidths of 480 MHz (2.32 to 2.80 GHz) for 2.4/2.5 GHz band, 810 MHz (3.22 to 4.03 GHz) for 3.5 GHz band, and 1,820 MHz (5.05 to 6.87 GHz) for 5.0 GHz band were obtained based on the impedance bandwidth. Measured 3D pattern and gains are displayed.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.6 s.336
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• pp.59-66
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• 2005

CMOS LC VCO for tri-bind wireless LAN applications was designed in 1.8V 0.18$\mu$m CMOS process. PMOS transistors were chosen for VCO core to reduce flicker noise. The possible operation was verified for 5.8GHz band (5.725$\~$5.825GHz), 5.2GHz band (5.150$\~$5.325GHz), and 2.4GHz band (2.412$\~$2.484GHz) using the switchable L-C resonators. To linearize its frequency-voltage gain (Kvco), optimized multiple MOS varactor biasing technique was used for capacitance linearization and PLL stability improvement. VCO core consumed 2mA current and $570{\mu}m{\times}600{\mu}m$ die area. The phase noise was lower than -110dBc/Hz at 1MHz offset for tri-band frequencies.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.11
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• pp.2518-2525
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• 2015

In this paper, we propose a UWB(Ultra Wide Band) antenna with CPW(Coplanar Waveguide) structure notched the 802.11a(5.15 ~ 5.825 GHz) band by using the U shaped slot. The proposed antenna not only shows Ultra-Wideband characteristic(3.1 ~ 10.6 GHz) suitable for UWB communications but has partially notched-band characteristic to reject 5 GHz WLAN band(5.15 ~ 5.825 GHz). The antenna is designed on an FR-4 substrate of which the dielectric constant is 4.4, and its overall size is $30mm(W){\times}20mm(L){\times}1mm(t)$. Fabricated antenna satisfied $VSWR{\leq}2$ in 3.1 ~ 10.6 GHz except for the band rejection of 5.15 ~ 5.825 GHz. And measured results of gain and radiation patterns characteristics displayed determined for operating bands.

• Journal of Advanced Navigation Technology
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• v.22 no.5
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• pp.449-455
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• 2018

For the size reduction, we propose a microstrip-fed monopole antenna with half X-slot in the radiation patch and cover WLAN dual band 2.4 GHz band (2.4 ~ 2.484 GHz) and 5 GHz band (5.15 ~ 5.825 GHz). The frequency characteristics such as impedance bandwidth and resonant frequencies were satisfied by optimizing the numerical values of various parameters, while the reflection loss in 5 GHz was improved by using defected ground structure (DGS). The proposed antenna is designed and fabricated on a FR-4 substrate with dielectric constant 4.3, thickness of 1.6 mm, and size of $24{\times}41mm^2$. The measured impedance bandwidths (${\mid}S_{11}{\mid}{\leq}-10dB$) of fabricated antenna are 450 MHz (2.27 ~ 2.72 GHz) in 2.4 GHz band and 1340 MHz (4.79 ~ 6.13 GHz) in 5 GHz band which sufficiently satisfied with the IEEE 802. 11n standard in dual band. In particular, radiation patterns which are stable as well as relatively omni-direction could be obtained, and the gain of antennas in each band was 1.31 and 1.98 dBi respectively.