• ETRI Journal
• /
• v.39 no.3
• /
• pp.336-344
• /
• 2017

In this paper, we propose a convenient microwave orbital angular momentum (OAM) mode generation and multiplexing method operating in the 18 GHz frequency band, based on a $2{\times}2$ uniform circular array and a $4{\times}4$ Butler matrix. The three OAM modes -1, 0, and +1 were generated and verified using spatial S-parameter measurements; the measured back-to-back mode isolation was greater than 17 dB in the full 17 GHz to 19 GHz range. However, the radiated OAM beam centers were slightly dislocated and varied with both frequency and the mode index, because of the non-ideal characteristics of the Butler matrix. This resulted in mode isolation degradation and transmission distance limitations.

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.238-239
• /
• 2007

In this study, the structural and microwave dielectric properties of the $Ba_{5}Nb_{4}O_{15}$ cation-deficient perovskite ceramics with sintering temperature were investigated. All sample of the $Ba_{5}Nb_{4}O_{15}$ ceramics were prepared by the conventional mixed oxide method and sintered at $1325^{\circ}C{\sim}1500^{\circ}C$. The bulk density, dielectric constant and quality factor of the $Ba_{5}Nb_{4}O_{15}$ ceramics were increased in the range of $1325^{\circ}C{\sim}1400^{\circ}C$ and decreased above the sintering temperature of 1400$^{\circ}C$. In the case of the $Ba_{5}Nb_{4}O_{15}$ ceramics sintered at 1400$^{\circ}C$ for 5h, the dielectric constant, quality factor and temperature coefficient of the resonant frequency (TCRF) were 39.55, 28,052GHz, 5.7ppm/$^{\circ}C$, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.25 no.4
• /
• pp.442-450
• /
• 2014

This paper is a study of the propagation characteristic of matching liquids in the skin-covered breast model. In order to evaluate the matching liquids, we investigated six kinds of matching liquids applied to proposed 1-D breast model from frequency range of 3~6 GHz. A uniform plane wave is projected / transmitted inside the multi-layered breast model. Then the propagation characteristics inside the model and the transmission loss of each matching liquids were analyzed. The studying method presented in the paper can be used in the breast cancer detection system, the field of cancer detection using human tissue and the field of other medical devices. This paper was applied to the breast cancer detection system. Consequently, these studies could be used to determine the suitable type of matching liquids for breast cancer detection system and to apply useful for performance analysis.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.51 no.7
• /
• pp.305-310
• /
• 2002

The microwave dielectric properties of Ba(Mg$_{1}$3/Ta$_{2}$3/O$_3$-Ba(Co$_{1}$3/Nb$_{2}$3/O$_3$[BMT-BCN] ceramics were investigated. The specimens were prepared by the conventional mixed oxide method with the sintering temperature of 15$25^{\circ}C$~1575$^{\circ}C$. It was found that Ba(Mg$_{1}$3/Ta$_{2}$3/O$_3$[BMT] and BCN formed a solid solution with complex perovskite structure. As increasing the mole fraction of BCN, dielectric constant increased while the temperature coefficient of resonant frequency was changed from positive to negative value. The highest value of quality factor, Q$\times$f$_{0}$=138,205GHz, obtained in the 0.9BMT-0.1BCN ceramics sintered at 1575$^{\circ}C$. In the range of x$\geq$0.4, the dielectric constant was about 30. The 0.55BMT-0.45BCN ceramics sintered at 15$25^{\circ}C$ for 5 hours showed the microwave dielectric properties of $\varepsilon$$_{r}$=30.21, Q$\times$f$_{0}$=85,789GHz and $\tau$$_{f}$=2.9015ppm/$^{\circ}C$.EX>.

• Atmosphere
• /
• v.27 no.1
• /
• pp.93-104
• /
• 2017

The effect of Advanced Microwave Sounding Unit-A (AMSU-A) observations on the short-range forecast in East Asia (EA) was investigated for the Northern Hemispheric (NH) summer and winter months, using the Forecast Sensitivity to Observations (FSO) method. For both periods, the contribution of radiosonde (TEMP) to the EA forecast was largest, followed by AIRCRAFT, AMSU-A, Infrared Atmospheric Sounding Interferometer (IASI), and the atmospheric motion vector of Communication, Ocean and Meteorological Satellite (COMS) or Multi-functional Transport Satellite (MTSAT). The contribution of AMSU-A sensor was largely originated from the NOAA 19, NOAA 18, and MetOp-A (NOAA 19 and 18) satellites in the NH summer (winter). The contribution of AMSU-A sensor on the MetOp-A (NOAA 18 and 19) satellites was large at 00 and 12 UTC (06 and 18 UTC) analysis times, which was associated with the scanning track of four satellites. The MetOp-A provided the radiance data over the Korea Peninsula in the morning (08:00~11:30 LST), which was important to the morning forecast. In the NH summer, the channel 5 observations on MetOp-A, NOAA 18, 19 along the seaside (along the ridge of the subtropical high) increased (decreased) the forecast error slightly (largely). In the NH winter, the channel 8 observations on NOAA 18 (NOAA 15 and MetOp-A) over the Eastern China (Tibetan Plateau) decreased (increased) the forecast error. The FSO provides useful information on the effect of each AMSU-A sensor on the EA forecasts, which leads guidance to better use of AMSU-A observations for EA regional numerical weather prediction.

• Journal of the Korea Concrete Institute
• /
• v.19 no.2
• /
• pp.179-188
• /
• 2007

Recently, the concern on the receipt of poor ready-mixed concrete in the construction field and the durability of concrete has been increased. Based on the such background, a large number of measuring methods of water content for fresh concrete have been developed and enforced in a developed country. In this study, to investigate practicality for quality control of ready-mixed concrete among various water content measurement techniques, microwave range method, air meter method and capacitance measurement method as measuring methods of water content were selected. Then, it was evaluated estimating performance of water content according to the change of binder types, fine aggregate types, absorption ratio, water content and water-binder ratio in series I and II. Also, it was examined influence on error occurrence of water content according to change of properties of used materials in series III. Finally, based on this study, it was proposed fundamental data to utilize measurement technique of water content to quality control of ready-mixed concrete in construction field.

• Current Optics and Photonics
• /
• v.5 no.4
• /
• pp.384-390
• /
• 2021

This paper presents a wide-range tunable wavelength-locking technology based on optoelectronic oscillation (OEO) loops for optical fiber sensors and microwave photonics applications, explains the theoretical fundamentals of the design, and demonstrates a method for locking the relative wavelength differences between a leader semiconductor laser and its follower lasers. The input of the OEO loop in the proposed scheme (the relative wavelength difference) determines the radio-frequency (RF) signal frequency of the oscillation output, which is quantized into an injection current signal for feedback to control the wavelength drift of follower lasers so that they follow the wavelength change of the leader laser. The results from a 10-hour continuous experiment in a field environment show that the wavelength-locking accuracy reached ±0.38 GHz with an Allan deviation of 6.1 pm over 2 hours, and the wavelength jitter between the leader and follower lasers was suppressed within 0.01 nm, even though the test equipment was not isolated from vibrations and the temperature was not controlled. Moreover, the tunable range of wavelength locking was maintained from 10 to 17 nm for nonideal electrical devices with limited bandwidth.

• Proceedings of the International Microelectronics And Packaging Society Conference
• /
• 2000.11a
• /
• pp.23-27
• /
• 2000

Simultaneous Switching Noise (SSN) propagated through parallel power and ground planes in high-speed multilayer printed circuit boards (PCBs) causes malfunction of both digital and analog circuits. To reduce SSN, decoupling capacitors are generally used in the PCBs. In this paper, we improve the equivalent circuit model of decoupling capacitor in high-frequency range to analyze the effect of SSN reduction accurately. The analysis is performed by the microwave and RF design system (MDS) method and the finite difference time domain (FDTD) method. We compared the results by the ideal capacitor model with those by the proposed model.

• Proceedings of the KIEE Conference
• /
• 1997.11a
• /
• pp.308-310
• /
• 1997

In this paper, to anlayze electromagnetic distribution, measure the variation of relative permittivity of Glass-epoxy substrate for Computer-main-board and Tenon substrate for handphone or PCS in the frequency range $100[MHz]{\sim}1[GHz]$, in room temperature. To measure relative permittivity, suggested the Microstripline method. As the frequency increase, the variation of relative permittivity of Glass-epoxy is bigger than Tefoln's. And simulate the electromagnetic distribution on the PCBs in the infinite region applying the open boundary condition with these results by Finite Element Method.

• ETRI Journal
• /
• v.35 no.4
• /
• pp.718-721
• /
• 2013

This letter proposes a novel calibration method for a multiport amplifier (MPA) to achieve optimum port-to-port isolation by correcting both the amplitude and phase of the calibration signals. The proposed architecture allows for the detection of the phase error and amplitude error in each RF signal path simultaneously and can enhance the calibrated resolution by controlling the analog phase shifters and attenuators. The designed $2{\times}2$ and $4{\times}4$ MPAs show isolation characteristics of 30 dB and 27 dB over a frequency range of 19.5 GHz to 22.5 GHz, respectively.