• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.12
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• pp.1438-1446
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• 2010

In this paper, we compared and analyzed the antenna characteristics such as bandwidth, efficiency, and readable range in terms of the size and the number of turns of the multiple meander RFID tag antenna in the UHF band. The sizes of the each antenna are $20.0{\times}19.7$, $25.0{\times}24.8$ and $30.0{\times}29.7\;mm^2$. The bandwidths of the antennas for VSWR<5.8 are 857~963 MHz, 844~965 MHz, and 844~968 MHz which cover the worldwide UHF RFID bandwidth. The readable range of the antenna was greatly affected by the efficiency and gain of the antenna which depends on the size and the number of turns of the meander antenna.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.2
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• pp.73-78
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• 2011

A frequency synthesizer for DAB applications is designed using $0.18{\mu}m$ CMOS process with 1.8V supply. NP-core type is chosen for VCO core to improve low power characteristic and symmetric characteristic of output waveform. VCO range is 1302.34 MHz - 1949.51 MHz using switchable capacitor bank and varactor bank. Varactor biases that improve varactor capacitance characteristics were minimized as two, $K_{vco}$(VCO gain) is maintained using technique of varactor bank switching. Intervals of $K_{vco}$ are maintained adding VCO frequency compensation logic. Each block of VCO and frequency synthesizer designed $0.18{\mu}m$ CMOS process with 1.8V supply is verified by Cadence Spectre, measured VCO consumes 9mA current, and is 39.8% tuning range, total power consumption of the frequency synthesizer is 18mW.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.1 s.116
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• pp.7-14
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• 2007

In this paper, the scan characteristics of phased array antenna consisted of rectangular open-ended waveguide with a triangular grid are investigated. An infinite array structure is analyzed by numerically solving the integral equation for the electric field over the waveguide aperture using waveguide mode function and Floquet mode function. Next, SEP(Scan Element Pattern) and SI(Scan Impedance) characteristics are simulated by CST's MWS(Microwave Studio) and Ansoft's HFSS(High Frequency Structure Simulator) for the finite and infinite array structures. Also, validity of these approaches is verified by comparing the calculated and simulated results with the measured ones for an $8{\times}8$ subarray. Within 10.5 % fractional bandwidth in the X-band, the fabricated subarray showed the flat gain characteristic in the scan range of ${\pm}45^{\circ}C$ in the E-plane(azimuth) and ${\pm}20^{\circ}C$ in the H-plane(elevation), and also showed the return loss characteristic of less than -10 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.5 s.120
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• pp.553-562
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• 2007

In this paper, we designed and implemented the system for telemetering ELF(Extremely Low Frequency) magnetic field intensity. The magnetic field measurement system used a 3-axis magnetic field sensor to measure the magnetic field with isotropy and the equalizer to compensate the frequency characteristic in band. By multiplexing three output signals of the magnetic field sensor in time domain, we got the uniform gain and frequency characteristic among three axes. This system was designed that the magnetic field measurement level range was $0.01{\sim}10.0\;uT$ and the measurement frequency band was $40{\sim}180\;Hz$. The control system would access to the magnetic field measurement system with RF and the maximum access distance was 1.0 km. We confirmed that the measurement level error of the fabricated system was within 5 %. The fabricated system was installed to a golf practice range where a high voltage power transmission line was crossed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.10
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• pp.2351-2358
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• 2014

In this paper, a design method for a compact CPW-fed slot antenna using SRRs is studied. The structure of the proposed slot antenna is a rectangular slot antenna loaded with SRR conductors inside the slot to reduce the antenna size. Optimal design parameters are obtained by analyzing the effects of the gap between the SRR conductors and slot, and the width of the SRR conductors on the input VSWR characteristic. The optimized compact slot antenna operating at 2.45 GHz band is fabricated on an FR4 substrate with a dimension of 36 mm by 30 mm. The length of the proposed compact slot antenna is reduced to 14.3% compared to that of a conventional rectangular slot antenna. Experiment results show that the antenna has a desired impedance characteristic with a frequency band of 2.4-2.49 GHz for a VSWR < 2, and measured gain of 2.3 dBi at 2.45 GHz.

• 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.

• Applied Biological Chemistry
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• v.41 no.5
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• pp.372-376
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• 1998

Internal mass transfer during osmotic dehydration of gingers in sugar solution was examined as a function of concentration, temperature and immersion time of those solutions using moisture loss, sugar gain, molality and rate parameter. Influence of osmotic dehydration on browning reaction and texture properties of air dried rehydrated was also evaluated. Increasing the concentration and temperature of sugar solutions increased moisture loss, sugar gain, molality and rate parameter. Water loss and sugar gain were rapid in the first 3 min and then changed gentle slope. Moisture loss during osmotic dehydration using a sugar solution $(60\;Brix,\;80^{\circ}C)$ with 18 min immersion time was 40.05 g moisture/100 g wet ginger which was 52% reduction of initial moisture content in ginger (83.02%, wet basis). The changes of rate parameter were more affected by temperature than by concentration of sugar solution. Minimum browning degree (O.D.=0.027) was carried out by osmotic dehydration in sugar solution $(40\;or\;50\;Brix,\;80^{\circ}C)$ with 15 min immersion time compared to control (O.D.=0.132). Influence of osmotic dehydration on puncture forces of 3 min rehydrated ginger in boiling water were $22{\sim}34%$ of reduction, while blanching treatment had not affected compared to those of control.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.2
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• pp.170-175
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• 2016

In order to transmit baseband signals through frequency dividing devices, we studied the transfer function of the device in the term of the baseband signal distortion. From the analysis, it is shown that the magnitude of the envelope signal is related to the mixer gain and the insertion loss of the low pass filter whilst the phase is the additional function with the 1/2 of the phase delay. For the purpose of the verification of the study, we designed a dynamic frequency divider at 1,400 MHz. The operating frequency range of the device is closely related to the conversion gain of mixers and the amplitude of input signal, and becomes wide as the conversion gain of mixers increases. The designed frequency divider operates between 0.9 GHz and 3.2 GHz, for -14.5 dBm input power. The circuit shows 20 mW power dissipation at $V_{DD}=2.5V$, and the simulation result shows that an amplitude modulated signal at 1,400 MHz with the modulation index of 0.9 was successfully downconverted to 700 MHz.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.2
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• pp.374-379
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• 2006

In this paper, the high Gain and the wideband microstrip patch antenna, which is applicable to 5 GHz band wireless LAN, is designed and fabricated. Firstly to widen the bandwidth of microstrip antenna, U-Slot in rectangular form patch is inserted and used the microstrip line-Coaxial probe feeding method. Secondly, the antenna gain is improved to be embodied in $2{\times}2$ array form. As a result, in this paper, is designed and fabricated 5 GHz Band wideband U-Slot $2{\times}2$ array patch antenna using microstrip line-coaxial probe feeder. The U-Slot $2{\times}2$ array patch antenna were fabricated on the PEC using press-technique that is based on the simulation results. And the Anritsu 37169A vector network analyzer has been used in measurement of a prototype antenna. As a result, it was measured that the superior characteristic of wideband showing approximately 1 GHz ($5.110 GHz{\sim} 6.142 GHz$) of input return loss (VSWR < 2) in resonant frequency of 5 GHz band. And the antenna gain is 13 dBi, in both the E-plane and H-plane measured at 5.15 GHz, 5.35 GHz, 5.50 GHz, and 5.87 GHz.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.921-924
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• 2005

We report low conversion loss and high LO to RF isolation 94 GHz MMIC resistive mixers based on 0.1 ${\mu}m$ InGaAs/InAlAs/GaAs metamorphic HEMT technology. The fabricated resistive mixers applied a one-stage amplifier on RF port of the mixer. By using the one-stage amplifier, we obtained the decrement of conversion loss and the increment of LO to RF isolation. So, we can obtain higher performances than conventional resistive mixers. The modified mixer shows excellent conversion loss of 6.7 dB at a LO power of 10 dBm. We also observed an extremely high isolation characteristic from the MMICs exhibiting the LO-RF isolation of 21 ${\pm}$ 0.5dB in a frequency range of 93.7${\sim}$ 94.3 GHz. The low conversion loss and high LO-RF isolation characteristics of the MMIC modified resistive mixers are mainly attributed to the performance of the MHEMTs exhibiting a maximum transconductance of 654 mS/mm, a current gain cut-off frequency of 173 GHz and a maximum oscillation frequency of 271 GHz.