• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.8
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• pp.765-768
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• 2015

In this paper, two ports feeding a microstrip patch antenna using a quadrature hybrid circuit was proposed to enhance the bandwidth for the global positioning system(GPS). The square patch was designed, and the probe feeding was applied. The quadrature hybrid chip circuit for two-port feeding was designed, and output ports that have a 90-degree phase difference feed to the patch antenna. The designed patch and quadrature hybrid circuit were implemented on an FR4 board, and were combined. The measurement of the bandwidth within a voltage standing wave ratio(VSWR) of 2: 1 and axial ratio(AR) in 3dB were 29 %BW(1,230~1,700 MHz) and 15.87 %BW(1,400~1,650 MHz), respectively. The peak gain at the GPS center frequency was measured at 2.75 dBi in an anechoic chamber.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.9
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• pp.384-391
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• 2003

The wideband annular ring slot antenna with concentric radiating structure and low impedance feedline has been presented. This antenna has been analyzed in compensation for FR-4 substrate with relative permittivity 4.3 and thickness 1 mm. As the measured 10 dB impedance bandwidth of the proposed antenna is 127.2%(2.17∼9.76 GHz), its bandwidth is much broader than maximum 82% bandwidth of a conventional annular ring slot antenna. Experimental results from 2 to 10 GHz are shown to be in good agreement with the simulation. And this antenna has a high gain above 4 dBi from 2 GHz to 10 GHz as well as a 24% size reduction and 42% area reduction than a circular slot antenna.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.12
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• pp.2763-2768
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• 2013

In this paper, a design method for a compact slot antenna for 5.8 GHz RFID band (5.725-5.875 GHz) is studied. The proposed slot antenna is size-reduced by bending both ends of the straight slot in "I"-shape, and a rectangular feed patch is located inside the slot. The effects of slot length, location of feed patch, and width and length of feed patch on the antenna performance are examined. A prototype antenna with optimized parameters for 5.8 GHz band is fabricated on an FR4 substrate and tested experimentally to verify the results of this study. The experimental results show that the frequency band for a VSWR < 3 ranges 5.72-6.13 GHz (bandwidth 410 MHz), and it corresponds fairly well with the simulated band 5.64-5.97 GHz (bandwidth 330 MHz). The fabricated antenna shows good radiation performance such as maximum power density in both directions normal to the slot plane, low cross-polarization level of < -20 dB, and realized gain > 0 dBi within the frequency band.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.9
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• pp.4095-4100
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• 2011

In this paper, a log periodic bow-tie dipole array (LPBDA) antenna for UWB communications is investigated. Bow-tie shaped dipole elements are used instead of general dipole elements for LPDA antennas and the input reflection coefficient and realized gain characteristics of the LPBDA as a function of a flare angle are analyzed. It turns out that as the flare angle of the bow-tie dipole elements is increased, the lowest operating frequency is shifted toward lower frequency and the operating frequency band is increased, but the average gain is decreased. However, the gain variation of the LPBDA is much decreased and the front-back ratio is improved compared to the LPDA. Standard LPDA and LPBDA with a flare angle of 13 degrees are fabricated on an FR4 substrate with a dielectric constant of 4.4 and a thickness of 1.6 mm. Measured gain for the LPDA ranges from 4 to 6.5 dBi at 3.1 to 10.6 GHz band, while that for the LPBDA is in the range of 4.2 to 5 dBi.

• Journal of the Institute of Convergence Signal Processing
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• v.16 no.4
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• pp.156-161
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• 2015

In this paper, a dual-polarized multi-band multi-layer antenna for a vehicle, which operates in the GPS, bluetooth, and DSRC bands, was implemented. The antenna was designed as a multi-layer structure, and a FR4-epoxy substrate with =4.4 and =1.6mm was used. GPS and DSRC antennas have circular polarized characteristics, and a single probe feeding method was applied. Simulated results by Ansys HFSS v11 was compared with the measured ones. The size of the optimally designed antenna is $67mm{\times}67mm{\times}4.8mm$, -10dB bandwidth of the anatenna was measured to be 820MHz, 127MHz, and 862MHz in each band, and 3dB AR bandwidth of the antenna was simulated to be 19MHz and 110MHz in GPS and DSRC bands. The results confirmed that suggested system satisfies the system requirements.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.3
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• pp.198-204
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• 2001

In this paper, a 3V 8-bit 200MSPS CMOS folding / interpolation A/D Converter is proposed. It employs an efficient architecture whose FR(Folding Rate) is 8, NFB(Number of Folding Block) is 4, and IR (Interpolating Rate) is 8. For the purpose of improved SNDR by to be low input frequency, distributed track and hold circuits are included. In order to obtain a high speed and low power operation, further, a novel dynamic latch and digital encoder based on a novel delay error correction are proposed. The chip has been fabricated with a 0.35${\mu}{\textrm}{m}$ 2-poly 3-metal n-well CMOS technology. The effective chip area is 1070${\mu}{\textrm}{m}$$\times$650${\mu}{\textrm}{m}$ and it dissipates about 230mW at 3.3V power supply. The INL is within $\pm$1LSB and DNL is within $\pm$1LSB, respectively. The SNDR is about 43㏈, when the input frequency is 10MHz at 200MHz clock frequency.

• Journal of Navigation and Port Research
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• v.39 no.6
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• pp.473-478
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• 2015

In this paper, we suggest a flexible multiband antenna which can be equipped on an inflatable life-jacket. The antenna can send distress alert and location data of survivors to assist rescue operation when crew or people are in distress. The antenna operate in three frequency bands such as VHF-DSC band (156MHz), COSPAS-SARSAT band (406MHz) and GPS band (1,575MHz). The GPS band is implemented with a square ring-slot planar antenna, the COSPAS-SARSAT band and the VHF-DSC band antenna is implemented by monopole type. In order to give flexibility of substrate to be equipped on life-jacket, FR4-epoxy substrate of thickness 0.2mm is used to make antenna. The reflection coefficients of the fabricated antenna are -8.8dB, -20.4dB and -10.7dB at each bandwidth like VHF-DSC, COSPAS-SARSAT and GPS band, respectively, when people are wearing life-jacket integrated multiband antenna.

• 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.

• The Korean Journal of Mycology
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• v.20 no.3
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• pp.240-251
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• 1992

To find antitumor components from higher fungi, the cultured mycelia of Paxillus atrotomentosus were extracted with hot water. The water soluble fraction was purified and separated by DEAE-cellulose ion exchange chromatography and Sepharose CL-4B gel filtration method. The separated fractions(Fr.) were designated CR A, B, C and D. Fr. A showed the highest inhibition ratio of 68.51% among the five tractions at a dose of 20 mg/kg/day. When Fr. A was examined for immunopotentiation activity, it increased the amount of the superoxide anion from activated macrophages to 1.1 fold and the number of plaques in hemolytic plaque assay to 2.3 fold, respectively. Otherwise, it did not show direct cytotoxity in sarcoma 180. Delayed type hypersensitiyity reaction showed that the decreased footpad swelling of tumor-hearing was restored to the normal. These results indicate that antitumor activity was exerted through immunopotentiation. Its chemical analysis showed 86.36% polysaccharide, 1.52% protein and 1.64% hexosamine. The polysaccharide consisted of fucose, galactose, glucose, mannose and xylose. This component was named paxillan.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.12
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• pp.2270-2275
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• 2011

The sintering behavior and microwave properties of ferrite ($Ba_3Co_{2-2x}Zn_{2x}Fe_{24}O_{41}$ ceramics) were investigated for microwave applications. Also PIFA type antenna with ferrite was simulated. All samples were prepared by the solid state reaction method and sintered at $1350^{\circ}C$. All ceramics had relatively density above of 92% compare with theoretical density of $Ba_3Co_2Fe_{24}O_{41}$ ceramics. From the XRD pattens, the Z-type phase was existed as main phase in $Ba_3Co_{2-2x}Zn_{2x}Fe_{24}O_{41}$ ceramics. The permittivity and permeability of $Ba_3Co_{2-2x}Zn_{2x}Fe_{24}O_{41}$ ceramics were increased with Zn additions and decreased rapidly over frequency of 200~600 MHz. Several PIFA type antennas with ferrite and FR4 were simulated. All antenna structure had return loss of less than -10 dB at each resonant frequency. Simulated antenna using both ferrite and FR4 showed size reduction of 25% without a significant decrement of efficiency.