• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.6
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• pp.71-76
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• 2010

In this paper, a 120 GHz local oscillator(LO) for the sub-harmonic mixer in the THz transceiver with a carrier frequency of 240 GHz was designed and fabricated. A 120 GHz local oscillator was composed of 40 GHz PLL(Phase Locked Loop), 40 GHz BPF(Band Pass Filter), frequency tripler and 120 GHz BPF. The commercial model of the frequency tripler was used. The measured result of the 40 GHz PLL showed the phase noise of -105 dBc/Hz at the 100 kHz offset frequency. The measured result of 120 GHz BPF showed the insertion loss of 1.3 dB at center frequency of 119 GHz with bandwidth of 5 GHz. The output power of 120 GHz LO was measured to 6.6 dBm.

• Journal of Advanced Navigation Technology
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• v.26 no.1
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• pp.29-34
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• 2022

In this paper, the design of a triple dipole quasi-yagi antenna operating in the 2.45 GHz and 5 GHz wireless LAN frequency bands and the 3.5 GHz WiMAX frequency band was studied. The proposed quasi-Yagi antenna consists of three dipoles connected in series with a V-shaped ground plane. The longest half-bow-tie-shaped dipole resonates in the 2.45 GHz band, whereas the medium-length dipole resonates at 3.5 GHz. The shortest dipole resonates in the 5 GHz band. By adjusting the length and width of the dipoles and the spacings between the dipoles, a triple-band directional antenna operating in the 2.45 GHz, 3.5 GHz, and 5 GHz bands are designed, and fabricated on an FR4 substrate with a size of 45 mm × 55 mm. It was confirmed that the fabricated antenna operates in the designed triple bands of 2.32-2.57 GHz, 3.26-3.69 GHz, and 4.50-6.56 GHz for a voltage standing wave ratio less than 2. Gain is maintained above 3 dBi in the three bands.

• ETRI Journal
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• v.35 no.3
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• pp.534-537
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• 2013

A compact monopole antenna excited by a conductor-backed coplanar waveguide (CBCPW) is developed for wireless USB dongle applications. The proposed antenna has a compact dimension of $14mm{\times}47.4mm{\times}3.5mm$, which is suitable for a USB dongle housing. A slotted elliptical patch and a CBCPW with vertical vias are employed to achieve a further size reduction and an improved impedance bandwidth. The measurement result demonstrates that the fabricated antenna resonates from 2.25 GHz to 10.9 GHz, which covers all of the important wireless communication bands, including WiBro (2.3 GHz to 2.4 GHz), Bluetooth (2.4 GHz to 2.484 GHz), WiMAX (2.5 GHz to 2.7 GHz and 3.4 GHz to 3.6 GHz), satellite DMB (2.605 GHz to 2.655 GHz), 802.11b/g/a WLAN (2.4 GHz to 2.485 GHz and 5.15 GHz to 5.825 GHz), and ultra-wideband (3.1 GHz to 10.6 GHz) services. The radiation characteristics of the proposed antenna when attached to a laptop are tested to investigate the influence of the keypad and the LCD panel of the laptop.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.7B
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• pp.727-736
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• 2002

In this paper, the broadband microstrip antenna with small size, thin-profile, conformability and ease of manufacture is proposed for providing PCS(down link: 1.75GHz∼1.78GHz, up link: 1.84GHz∼1.87GHz) '||'&'||' IMT-2000(down link: 1.92GHz∼1.98GHz, up link: 2.11GHz∼2.17GHz) services simultaneously. By using double U-slots and matching stub, the bandwidth and operating performance of printed antenna was significantly improved, with need for a complex fabrication procedure. We have also studied the various parameters of the U-slot$_2$for the performances of the antenna. Impedance bandwidth of the wideband microstrip antenna with the double U-slots is about 30.45% (VSWR<2)

• JSTS:Journal of Semiconductor Technology and Science
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• v.7 no.4
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• pp.281-286
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• 2007

In this paper, sub-circuits for 24 GHz phase locked 100ps(PLLs) using $0.5{\mu}m$ SiGe HBT are presented. They are 24 Ghz voltage controlled oscillator(VCO), 24 GHz to 12 GHz regenerative frequency divider(RFD) and 12 GHz to 1.5 GHz static frequency divider. $0.5{\mu}m$ SiGe HBT technology, which offers transistors with 90 GHz fMAX and 3 aluminum metal layers, is employed. The 24 GHz VCO employed series feedback topology for high frequency operation and showed -1.8 to -3.8 dBm output power within tuning range from 23.2 GHz to 26 GHz. The 24 GHz to 12 GHz RFD, based on Gilbert cell mixer, showed 1.2 GHz bandwidth around 24 GHz under 2 dBm input and consumes 44 mA from 3 V power supply including I/O buffers for measurement. ECL based static divider operated up to 12.5 GHz while generating divide by 8 output frequency. The static divider drains 22 mA from 3 V power supply.

• Journal of Advanced Navigation Technology
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• v.21 no.2
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• pp.193-199
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• 2017

In the paper, a dual band-notched monopole antenna is proposed for 2.4 GHz WLAN (2.4 ~ 2.484 GHz) and UWB (3.1 ~ 10.6 GHz) applications. The 3.5 GHz WiMAX band notched characteristic is achived by a pair of L-shaped slots instead of the previous U-shaped slot on the center of the radiating patch, whereas the 7.5 GHz band notched characteristic is achived by C-shaped strip resonator placed near to the microstrip feed line. The measured impedance bandwidth (${\mid}S_{11}{\mid}{\leq}-10dB$) is 8.62 GHz (2.38 ~ 11 GHz) which is sufficient to cover 2.4 GHz WLAN and UWB band, while measured band-notched bandwidths for 3.5 GHz WiMAX and 7.5 GHz bnad are 1.13 GHz (3.15 ~ 4.28 GHz) and 800 MHz (7.2 ~ 8 GHz) respectively. In particular, it has been observed that antenna has a good omnidirectional radiation patterns and higher gain of 2.51 ~ 6.81 dBi over the entire frequency band 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.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.3
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• pp.1-6
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• 2008

A dual band I/Q modulator which converts baseband input signals to 2.4GHz or 5GHz RF output has been proposed. The dual band I/Q modulator for 2.4GHz and 5GHz wireless LAN applications consists of $90^{\circ}$ phase shifter and wideband mixer. The I/Q modulator showed 15dB conversion loss at 2.4GHz and 16dB conversion loss at 5GHz. The sideband suppression is about 15dBc at 2.4GHz and 16dBc at 5GHz. Measured data shows 8.5% EVM at 2.4GHz, and 10% EVM at 5GHz for QPSK with symbol rate of 11Mbps. A carrier rejection is about 40dBc at 2.4GHz/5GHz band, and the I/Q modulator satisfied the output wireless LAN spectrum mask with baseband input signal.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.2
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• pp.257-262
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• 2017

In this paper, we proposed a rectangular planar monopole antenna with a double sleeve that applied to a half-cut and a discontinuous feed structure. A rectangular planar monopole antenna with a double sleeve was cut in half along the magnetic symmetry line, and impedance matching was achieved by a discontinuous structure was applied to a feeder and by adjusting the double sleeve gap. We used the HFSS simulator of ANSYS company to confirm the antenna parameter property, and the antenna size was $21{\times}40mm^2$. In the proposed antenna, the simulation frequency range with VSWR of 2 or less was 2.6GHz to 10.25GHz. The bandwidth was 7.65GHz. The frequency range of the fabricated antenna was 3.3GHz to 9.75GHz, and the bandwidth was 6.45GHz. The measured radiation pattern frequencies were 3.5GHz, 5.5GHz, 7.5GHz, and 9.5GHz. A radiation pattern similar to the dipole antenna pattern was obtained at all frequencies.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.2
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• pp.67-74
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• 2009

In this paper, the multi-band antenna with CPWG(Coplanar Waveguide with Ground) feed for telematics mobile devices is designed and fabricated. The proposed antenna improves the return loss characteristic by using open-circuited stub matching and rectangular slot in the radiation patch. In addition, CPWG structure makes up for the drawback of the CPW which is variation of impedance matching according to the gap variation of the feed line and the ground. The fabricated antenna has 1.4GHz ($1.43GHz{\sim}2.83GHz$, 65%) band width on -10dB (VSWR<2) and the maximum gains are 0.8dBi, 1.34dBi, 2.41dBi, 2.53dBi, 2.6dBi and 1.51dBi on each resonant frequency that are GPS $(1.564GHz{\sim}1.585GHz)$, PCS/DCS $(1.710GHz{\sim}1.984GHz)$, WCDMA $(2.170GHz{\sim}2300GHz)$, Bluetooth/Wi-Fi/WLAN $(2.4GHz{\sim}2.483GHz)$, WiBro $(2.3GHz{\sim}2.4GHz)$, SDMB $(2.605GHz{\sim}2.655GHz)$. It also has an omni-directional radiation pattern of H-Plane.