• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.1
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• pp.45-52
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• 2009

In this paper, a new rectenna is presented for the wireless transmission of microwave power using dipole antenna (Quasi Yagi effect) and rectifier of CPS resonator structure. The dipole antenna with CPW feedline has high peak gain than a general dipole antenna. A ground plane of CPW is used to reflect a dipole as a Yagi antenna. Therefore, the new rectenna receives the RF power better than the one using general dipole. A RF-to-DC conversion efficiency of 61 % using a 1.4 $k{\Omega}$ load resistor is obtained at 5.8 GHz.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.1
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• pp.286-290
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• 2017

In this paper, we have proposed a hexagonal patch UWB antenna with a band notch characteristic where the notch band of 5.15 ~ 5.85 GHz band of WLAN was induced by inserting a circular slit in the patch. The impedance bandwidth of the proposed antenna meet the band width criteria of UWB communication system where is mentioned as frequencies range form 3.1 ~ 11.8 GHz. The characteristic band at 5.2 ~ 5.8 GHz notch band was observed. The radiation pattern of the antenna shows a directinal radiation pattern at $0^{\circ}$ and $180^{\circ}$ in XZ-plane and YZ-plane is an omni-directional pattern, respectively. In addition, it is observed that increase in frequency results in increases of the antenna gain whereas the notch band section is decreased. The proposed antenna was designed TRF-45 substrate with thickness of 1.62 mm, a loss tangent of 0.0035, a relative permittivity of 4.5 and designed were used Ansys Inc. HFSS.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.8
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• pp.64-72
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• 2010

This paper presents a wide range VCO with fine coarse tuning step using a sigma-delta modulation technique for UWB frequency synthesizer. The proposed coarse tuning scheme provides the low effective frequency resolution without any degradation of phase noise performance. With three steps coarse tuning, the VCO has wide tuning range and fine tuning step simultaneously. The frequency synthesizer with VCO was implemented with 0.13 ${\mu}m$ CMOS technology. The tuning range of the VCO is 5.8 GHz~6.8 GHz with the effective frequency resolution of 3.9 kHz. It achieves the measured phase noise of -108 dBc/Hz at 1 MHz offset and a tuning range 16.8 % with 5.9 mW power. The figure-of-merit with the tuning range is -181.5 dBc/Hz.

• Journal of IKEEE
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• v.16 no.2
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• pp.69-75
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• 2012

In this paper, microstrip array antenna is proposed for the wireless communication of DSRC(dedicated short range communication) scheme at 5.8GHz, which works as a part of the Navigation terminal. The microstrip patches minimized from a rectangular microstrip antenna with a half wavelength are arrayed to be mounted on the narrow and long area in the top side of the navigation terminal. Besides, the array antenna can limit its own beamwidth to the driving lane and has better directivity. It is simulated to verify the validity of the proposed application. The prototype fabricated has a volume of $18{\times}40{\times}0.8mm^3$. From the measurement, it has circular polarization performance of 4dB axial ratio over 40MHz frequency band. In addition, antenna gain of 6.2dBi and 3dB beamwidth of $70^{\circ}$ at cross section of driving lane have been achieved.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.11
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• pp.842-850
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• 2018

In this paper, the design and fabrication of a frequency-locked-loop(FLL) 5-GHz oscillator with a single resonator is presented. The proposed oscillator is the simplified version of the previous FLL oscillator with two separate resonators in the VCO and frequency detector. The resonator is commonly used in the VCO and frequency detector of the proposed oscillator configuration. The 5-GHz oscillator is implemented on the hetero-multilayer substrate composed of a Rogers' RO4350B laminate, which has excellent high-frequency performance, and the commercial FR4 three-layer substrate. The frequency locking occurs at approximately 5 GHz and has an output power of 3.8 dBm. The phase noise has a free-run VCO phase noise at frequencies above 1 kHz, and an FLL background noise at frequencies below 1 kHz. For this loop-filter, the phase noise showed an improvement of approximately 12 dB at the offset-frequency of 100 Hz.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.5
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• pp.688-693
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• 2022

In this paper, channel propagation path loss was measured in building corridors for frequency bands of 3.7 GHz and 28 GHz, which are used in 5G mobile communication, and compared and analyzed with CI (Close-In) and FI (Floating-Intercept) channel models. To measure the propagation path loss, the measurement was performed while moving the receiver (Rx) from the transmitter (Tx) by 10 m. As a result of the measurement, the PLE (Path Loss Exponent) values of the CI model at 3.7 GHz and 28 GHz were 1.5293 and 1.7795, respectively, and the standard deviations were analyzed as 9.1606 and 8.5803, respectively. In the FI model, 𝛼 values were 79.5269 and 70.2012, 𝛽 values were -0.6082 and 1.2517, respectively, and the standard deviations were 5.8113 and 4.4810, respectively. In the analysis results through the CI model and the FI model, the standard deviation of the FI model is smaller than that of the CI model, so it can be seen that the FI model is similar to the actual measurement result.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.11 s.353
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• pp.185-191
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• 2006

DSRC((Dedicated Short Range Communication) is dedicated short range communication for wireless communications between RSE(Road Side Equipment) and OBE(On-Board Unit) within vehicle moving high speed. In this paper, we implemented 5.8GHz DSRC modem according to Korea TTA(Telecommunication Technology Association) standard and investigated implementation results and design process for SoC(System on a Chip) embedding ARM CPU which control overall signal and process arithmetic work. The SoC is implemented by 0.11um design technology and 480pins EPBGA package. In the implemented SoC ($Jaguar^{TM}$), 5.8GHz DSRC PHY(Physical Layer) modem and MAC are designed and included. For CPU core ARM926EJ-S is embedded, and LCD controller, smart card controller, ethernet MAC, and memory controller are designed as main function.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.5 s.108
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• pp.423-429
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• 2006

This paper deals with research for development of electromagnetic wave absorbers in sheet type for mobile phones. By controlling the sendust ratio, the $Al(OH)_3$ coating, the thickness, the kind of binders, and the milling time, electromagnetic wave absorbers were prepared and examined. Central frequency shills toward lower 2.2 GHz, 1.29 GHz, 842 MHz with increasing thickness 1 mm, 2 mm, 3 mm of the absorber, and absorption ability controlled each 2.2 GHz to 1.91 GHz, 1.29 GHz to 801 MHz, 842 MH2 to 801 MHz adjust sendust amount from 80 wt% to 85 wt%. The absorption band of the electromagnetic wave absorber coated with $Al(OH)_3$ becomes larger than that of non-coated one. Sendust composite microwave absorbers mixed with CPE were prepared at $70^{\circ}C$ in temperature. The fabricated electromagnetic wave absorbers show a reflection coefficient 5.76 dB at 1.8 GHz in thickness of 0.85 mm.

• 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.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.5
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• pp.24-29
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• 1993

The national standards of microwave power in X-band and Ku-band were established using the waveguide microcalorimeters and have been disseminated to the related industries to contribute to industrial development. Through the comparisons and analysis of the measured effective efficiencies for waveguide thermistor mounts in the recent years, the accuracy for maintenance of power standards was confirmed.