• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.3
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• pp.395-400
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• 2021

In this paper, the wideband patch antenna is simulated and manufactured for the wireless LAN of 5GHz band that is defined in IEEE 802.11a. In the 802.11a, 200 channels of 675MHz are defined. Therefore, the bandwidth is needed more than 12.3%. For the wideband characteristics, low dielectric constant is realized with the multi-layer of 2 teflon substrates and the air dielectric layer and the feeding method of the coupled-line is used. Optimized wideband patch antenna is simulated with the return loss of 38.99dB at the center frequency of 5.43GHz and the bandwidth of 12.9%. The gain of manufactured patch antenna is 4.38, 4.52, and 5.12dBi at the channel number of 46, 56, and 153, respectively.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.4
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• pp.756-760
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• 2007

The $(1-x)Mg_4Ta_2O_9-xwt%TiO_2\;(x=5\sim20)$ microwave dielectric ceramics were prepared by solid-state reaction method and sintered at $1450^{\circ}C$. According to the X-ray diffraction data, the $Mg_4Ta_2O_9-xwt%TiO_2$ ceramics had main phase of $Mg_4Ta_2O_9$ and $MgTi_2O_5$ peaks were added by increasing of $TiO_2$ addition. Microwave dielectric properties of the $Mg_4Ta_2O_9-xwt%TiO_2$ ceramics were influenced by $MgTi_2O_5$ phase and properties of $TiO_2$. There was a little decrement of the quality factor from 116,800GHz of pure $Mg_4Ta_2O_9$ to 100,100GHz of 15wt% $TiO_2$ added one. But there was excellent improvement in temperature coefficient of the resonant frequency (TCRF) by addition of 15wt% $TiO_2$. The dielectric constant quality factor and TCRF of the $Mg_4Ta_2O_9-xwt%TiO_2$ ceramics sintered at $1450^{\circ}C$ were $13.08\sim16.41,\;45,000\sim165,410GHz,\;-24.82\sim+3.88ppm/^{\circ}C$, respectively, depending on the value of x. Simulated dielectric resonator (DR) with $Mg_4Ta_2O_9-15wt%TiO_2$ ceramics had the operating frequency of 11.97GHz and $S_{2,1}$ of -35.034dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.12
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• pp.1212-1218
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• 2014

This paper proposes a planar bow-tie UWB antenna by modifying the ground patch of a reference bowtie-monopole antenna satisfying low band of UWB. The proposed antenna was implemented with five-angled ground patch to be operated in whole UWB band, while the reference antenna had a ground patch of half circle type. The measured return loss satisfies less than -10 dB in 3.1~10.6 GHz, except 4.9~5.8 GHz rejection band. The measured radiation pattern is almost the same with that of the monopole antenna. The radiation gain reduction is about 8 dB at rejection band.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.9
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• pp.63-69
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• 2007

The directivity of crossed waveguide directional coupler is generally decreased according as coupling coefficient of it increase. In this paper, the geomertical parameters of crossed slot pair for directivity improvement is modified and the formulas for design of it are proposed. The crossed waveguide directional coupler designed upon the formulas is fabricated with the WR42 waveguide in K-band. The measured results show that the coupling coefficient is 21.5 dB and directivity is minimum 23.9 dB over the operating frequency from 18GHz to 26.5GHz.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.6
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• pp.1049-1056
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• 2016

In this paper, a design method for a compact dual-band slot antenna with bent slot is studied. Bent slots are added on the rectangular slot of the proposed antenna for dual-band operation. The rectangular slot is fed by a coaxial cable by placing a rectangular feeding patch inside the slot. When the bent slots are added onto the both corner of the upper side of the rectangular slot symmetrically, a new resonant frequency is created in low frequency because of the increasement of the slot length. A prototype of the proposed dual-band slot antenna operating at 2.45 GHz WLAN band and 4.50-8.30 GHz band including 5GHz WLAN band is fabricated on an FR4 substrate with a dimension of 30 mm by 30 mm. Experiment results show that the antenna has a desired impedance characteristic with a frequency band of 2.40-2.49 GHz and 4.33-9.85 GHz for an input reflection coefficient < -10 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.5
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• pp.397-400
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• 2018

This paper presents a miniaturized 65 nm CMOS 30~46 GHz wideband amplifier. To minimize the chip area, coupled inductors are used in the matching networks. The measurement shows that the fabricated amplifier exhibits 9.3 dB of peak gain, 16 GHz of 3 dB bandwidth, and 42 % fractional bandwidth. The measured input and output return losses were more than 10 dB at 35.8~46.0 GHz and 28.6~37.8 GHz, respectively. The chip consumes 42 mW at 1.2 V. The measured group delay variation is 19.1 ps within the 3 dB bandwidth and the chip size excluding the pads is $0.09mm^2$.

• Journal of Advanced Navigation Technology
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• v.27 no.6
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• pp.815-820
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• 2023

In this paper, the design method of a miniaturized chipless RFID tag using a modified bent H-shaped slot was proposed. The proposed modified bent H-shaped slot was appended on the rectangular conductor plate printed on one side of a 20 mm × 50 mm FR4 substrate with a thickness of 0.8 mm. The resonant dip frequency of the bistatic RCS for the proposed modified bent H-shaped slot was compared with the cases when the H-shaped, U-shaped slot, and bent H-shaped slots were added, respectively, on the conductor plate. The simulated resonant dip frequencies for H-shaped, U-shaped, and bent H-shaped slots were 5.907 GHz, 4.918 GHz, and 4.364 GHz, respectively. When the proposed modified bent H-shaped slot was added, the resonant dip frequency was decreased to 3.741 GHz, and, therefore, the slot length was reduced by 36.7% compared to the H-shaped slot case. Experiment results show that the resonant dip frequency of the fabricated modified bent H-shaped slot was 3.9 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.3
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• pp.211-218
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• 1996

Theorectical and experimental studies of On-Glass antenna in the 1.9GHz bandare performed. In this paper, the structure of designed On-Glass antenna consists of a 5/8-wavelength upper segment and quarter-wavelength lower segment separated by phasing coil. On-Glass antenna may be resonated by the use of suitably spaced phasing coil in series with the antenna wire. This tuning structure leads to an improvement in antenna efficiency. And then, this can be very useful for installation where limited space like automobil is available. The analytical method is based on collocation method with pulse function. The results obtained from numerical method are presented and compared with an experimental evaluation. From this, the VSWR, gain, radiation pattern, and bandwidth of the On-Glass antenna are analyzed.

• Journal of IKEEE
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• v.4 no.2 s.7
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• pp.202-211
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• 2000

Utilizing the circuit simulator SPICE, we designed a 1.9GHz CMOS up-conversion mixer and explained in detail the simulation procedures including device modeling for the circuit design. Since the measured characteristics of the chip fabricated using the $0.5{\mu}m$ standard CMOS process had shown a big deviation from the characteristics expected by the original simulations, we tried to figure out the proper reasons for the discrepancies. Simulations considering the discovered problems in the original simulations have shown the validity of the simulation method tried for the design. We have shown that the utilized standard CMOS process can be used for the implementation of the chip characteristics similar to those of the equivalent chip fabricated using the GaAs MESFET process.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.10A
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• pp.1031-1036
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• 2006

This paper proposes a novel BPF structure with less insertion loss and small size instead of the existing coupled line BPF for the output of the tripler using APDP (Anti-Parallel Diode Pair). This proposed BPF consists of the interdigital capacitor and spiral open stub. The proposed BPF has the insertion loss of less than 0.7dB within the band $(16.41{\sim}19.23GHz)$. The conversion loss of the tripler is about $16.6{\sim}18.5dB$ $(flatness<{\pm}1dB)$ at $5.72{\sim}6.28GHz$ of fundamental frequency. Its fundamental frequency and the fifth harmonic suppression characteristic at 6GHz are -32.16dBc and -44.6dBc, respectively And its phase noise attenuation characteristic is about 9.5dB at 100kHz.