• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.581-584
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• 2002

In this work, a CPW resonator was designed and fabricated to investigate the basic microwave properties, such as effective dielectric constant, of BST thin films. Their properties were used as basic data to simulate and design CPW tunable bandpass filter. We also report on gold/$Ba_{0.5}Sr_{0.5}TiO_3$(BST) ferroelectric thin film C-band tunable bandpass filters(BPFs) designed and fabricated on magnesium oxide substrates using CPW structure. The 2 pole filter was designed for a center frequency of 5.88 GHz with a bandwidth of 9 %. The BST based CPW filter offers a high sensitivity parameter as well as a low loss parameter. The tuning range for the bandpass filter with CPW structure was determined to be 170 MHz.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.11 no.3
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• pp.153-163
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• 1986

GaAs, one of the III-V compounding semicondnctors, has been widely employed as base materials for the fabrication of the ultra-high-speed devices in the filelds of DBS, optical communications, MMIC'S and digital IC'S. There have been some reports on 4Kx4bit SRAM by D/E MESFET'S, 4K bit SRAM by HEMT'S, and receiver front ends for X-band by MMIC technologies, respectively. This paper reviews GaAs materials, wafer fabrication processes, device applications, and design aspects, and, finally, descusses the future of the ultra-high-spped-devices.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.1A
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• pp.77-83
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• 2004

Parallel coupled microstrip bandpass filter is widely used in microwave circuits. But this filter limits the filter applications because of the narrow bandwidth and the spurious passband at twice the basic passband frequency. In order to solve this problem, a method of the asymmetrical coupled microstrip lines on composite dielectric substrate is presented. Closed form method is used to analyze the asymmetrical coupled microstrip lines on composite dielectric substrate. An experimental filter is fabricated over $33\%$ bandwidth centered at 9GHz. Compared with the filter on a single substrate, this filter on composite substrate shows improvement of the spurious passband.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.616-619
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• 2003

This work presents the design, fabrication and microwave performance of distributed analog phase shifter (DAPS) fabricated on $(Ba,\;Sr)TiO_3$ (BST) thin films for X-band applications. Ferroelectric BST thin films were deposited on MgO substrates by pulsed laser deposition. The DAPS consists of high impedance coplanar waveguide (CPW) and periodically loaded tunable BST interdigitated capacitors (IDC). In order to reduce the insertion loss of DAPS and to remove the alteration of unloaded CPW properties according to an applied dc bias voltage, BST layer under transmission lines were removed by photolithography and RF-ion milling. The measured results are in good agreement with the simulated results at the frequencies of interest. The measured differential phase shift based on BST thin films was $24^{\circ}$ and the insertion loss decreased from 1.1 dB to 0.7 dB with increasing the bias voltage from 0 to 40V at 10 GHz.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1332-1-1332-4
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• 1998

This paper described design and simulation of the high-Tc superconducting (HTS) microstrip bandpass filter (BPF) on MgO substrate using $Y_1Ba_2Cu_3O_{7-x}$ films that show superconductivity ${at \fallingdotseq}90$ K. Design parameters for the characteristic of the bandpass filter in Ku-band were obtained by approximate design formulas. It used parallel coupled stripline stepped impedance resonators (SIR). Microwave design system, MDS(EEsorf S/W) was used to derive the optimal pattern of the filters and to simulate frequency response. In computer-aided results, optimally designed HTS filters got good performance compared with the gold counter-parts on frequency response $S_{21}$, $S_{11}$.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.9
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• pp.1374-1379
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• 2015

Time Domain Reflectometry(TDR) using microwave bands, including broadband spectrum that occurs at the range of rates that start between partial discharge position it easier to make the techniques that could be measured. Partial discharge in the Gas Insulated Switchgear(GIS), the dielectric constant in the band more than GHz different the insulating material if you want to organize, and the insulating material regardless of how partial discharge position in the SF6 gas Partial Discharge by applying the heritability estimated its position, but the position error occurred about 23 percent of the existing way, correct in not suitable location tracking the outbreak PD. This technique the rate of other dielectric that make up the power apparatus heterology is measured at the function to slow the progression of the electromagnetic waves apart by calculating the partial discharge as the location, A simple way to track. Dielectric using other methods proposed new structure can calculate the speed of heritability PD is occurring can measure.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.6
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• pp.1-6
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• 1989

Narrowband bandpass weveguide filters using inductive post obstacles in rectangular waveguide are designed and constructed to have an equal-ripple bandwidth of 50MHz (0.56% fractional band-width) at a center frequency of 9GHz. Both the triple-post and the single-post configurations are realized and compared. The measured center frequency, bandwidth, and attenuation characteristics for both filters show good agreement with the theoretical calculations. When the two filters are compared, the insertion loss characteristic of the triple-post filter is better than that of the single-post filter by 0.8dB at the passband.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.10
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• pp.1121-1127
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• 2010

This paper describes the equivalent circuit of $45^{\circ}$ layer, one of $11.25^{\circ}$, $22.5^{\circ}$, and $45^{\circ}$ phase shift layers, which are needed for X-band Radant lens 4-bit phase shifter. The equivalent circuit is extracted by comparing the CST's MWS results with the Agilent's ADS results for $45^{\circ}$ phase shift layer. The simulated result is compared with the measured one. Using the extracted equivalent circuit, the phase bit simulation results of 4-bit Radant lens are also presented.

• Progress in Medical Physics
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• v.4 no.1
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• pp.41-53
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• 1993

The electron spin resonanec of sigle crystals of L-alanine have been observed at T=300K, 100K and analyzed for different orieantations of the crystal in the magnetic field and at microwave frequency X-band. The stable free radical profuced by the irradiation is proved to be of the form CH$_3$CHR, where R is a group which has no nuclei with detectable coupling A notable dependence on temperature of the absorption was observed in the range from 1100K to 2l0K. It was concluded that the reorietation of the methy group of the radical H$_3$CCHR is quenched at low temperature.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.4
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• pp.143-152
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• 2016

In this paper, a MMIC double balanced mixer that can be applied to the tele-communication band is designed and LO power optimization for the mixer is discussed. The chip of the MMIC double-balanced mixer is fabricated on GaAs substrate with the size of $4{\times}4mm^2$. Optimization study of LO power for the MMIC double-balanced mixer proposed in this paper is conducted for the Input IP3 (IIP3) regarding on the linearity of the input signal. When LO power level of+16 dBm is applied to the mixer, IIP3 is obtained to be approximately 23.2 dBm, which is the most outstanding characteristic.