• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.800-804
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• 1995

The complex permeability dispersions and the microwave absorbing phenomena are investigated in ferrite microwave absorber. The complex permeability of NiZn ferrite, NiZnCo ferrite, and Y-type hexagonal ferrite were measured in 200MHz-14GHz range. Two types of resonances, the domain wall and the spin rotational resonance, were observed. With a ferrite particle with a diameter of about $1\;\mu\textrm{m}$, only spin rotational resonance were observed. The theoretical matching frequency is determined by plotting the measured complex permeability locus on the impedance matching solution map. One or two impedance matching phenomena are observed in the ferrite absorbers according to their complex permeability loci on the impedance matching solution map. The first matching frequency, found in the ferrite-rubber composites, which was higher than that of spin rotational resonance, increased with spin rotational resonance frequency.

• International Journal of Computer Science & Network Security
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• v.23 no.3
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• pp.203-207
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• 2023

A frequency reconfigurable antenna based on graphene and used for multi-band wireless communications is presented in this article. The proposed antenna, which consists of two radiating rectangular loops with a graphene extension, is analyzed for Global Positioning System (GPS) and Iridium applications. Its operating frequency is tuned through the implementation of a layer of graphene and thereby adjusting the applied gate bias. Furthermore, the results show a novel use of graphene for microwave frequencies while achieving a frequency reconfiguration with an improvement of the impedance matching and the gain. The results also prove the importance of graphene, with its exceptional properties, for a promising future in nano-electronics.

• The Journal of the Korea Contents Association
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• v.4 no.4
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• pp.171-178
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• 2004

Radio frequency (RF) microwave can be used to predict glucose concentration in a sample. This paper presents preliminary results in determining the concentration by measuring relative permittivity in the solutions of distilled water, saline, human serum, and human blood containing glucose. It was shown that the microwave method has larger penetration depth of about 100times of NIR, than NIR technique in measuring glucose concentration for the tissue like a human muscle. The larger penetration depth of the method has advantages because it is more useful to detect glucose in a human body non-invasively. In the experiments, sensitivity for detecting glucose concentration in blood solutions was almost 57mg/dl at the frequency of approximately 5.8GHz.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.8
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• pp.641-644
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• 2009

We have studied on the microwave characteristics for the meander type inductors on the MgO substrates and $Al_2O_3$ substrates by employing 3-D high frequency simulation, respectively. Proper designs of meander type inductors were proposed and confirmed through the high frequency simulations, 5, 7, 9, 11, and 13 turns meander type inductors have been choose to analyze the electrical properties for the microwave passive component applications. The Al top electrodes have 282 nm length, 45 nm width, 100 nm thickness and 15 nm gap. The simulations were carried out from 50 MHz to 30 GHz, Frequency dependent inductances and quality factor were calculated by employing the equivalent circuit model of meander type inductors. The self resonances frequency of meander type inductor were shifted from high frequency to low frequency range as the number of the turn of inductors was increased. From the microwave simulations, the inductances and quality factors of meander type inductors were extracted through the scattering parameter.

• 한국초전도학회:학술대회논문집
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• v.10
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• pp.65-65
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• 2000

Microwave response of intrinsic Josephson junctions in mesa structure formed on HgI2-intercalated Bi2Sr2CaCu2O8+x single crystals was studied in a wide range of microwave frequency. With irradiation of 73${\sim}$76 GHz microwave, the supercurrent branch becomes resistive above a certain onset microwave power. At low current bias, the current-voltage characteristics show linear behavior, while at high current bias, the resistive branch splits into multiple sub-branches. The voltage spacing between neighboring sub-branches increase with the microwave power and the total number of sub-branches is almost identical to the number of intrinsic Josephson junctions in the mesa. All the experimental results suggest that each sub-branch represents a specific mode of collective motion of Josephson vortices generated by the microwave irradiation. With irradiation of microwave of microwave of frequency lower than 20 GHz, on the other hand, no branch splitting was observed and the current-voltage characteristics exhibited complex behavior at hlgh blas currents. This result can be explained in terms of incoherent motion of Josephson vortices generated by non-uniform microwave irradiation.

• Journal of the Korean Institute of Telematics and Electronics
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• v.16 no.3
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• pp.49-56
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• 1979

A new microwave frequency disriminator in MIC is described which was developed using realization theory appropriate to a transmission line frequency discriminator designed to be used in the VHF range. It is experimentally verified that the discriminator is linear in a 600 MHz bandwith and has VSWR less than 1.2 in that range in agreement with the theoretical model.

• Journal of the Korean Institute of Telematics and Electronics
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• v.16 no.5
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• pp.42-48
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• 1979

In this paper, it is shown that a microwave frequency discriminator can be realized by use of a simple ring resonator. Its characteristics have been analyzed by employing Green's function and verified experimentally. The maximum frequency bandwidth obtained from the experiments is 45MHz at S-band(center frequency 50=3GHz).

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1992.10a
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• pp.2-29
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• 1992

According to the increase of occupation density of microwave frequency band on use microwave environments have been congested extensively. For shielding unnecessary electromagnetic wave of preventing the electromagnetic wave reflection a good conductor a low resistive material or a lossy material is mainly used. As a method to measure the absorbing characteristics of microwave absorber the fundamental microwave measuring method can be used. There is however a big problem in measuring errors since the wavelength of microwave is very short especially as in the case as microwave absorber for RADAR. Therefore this research aimed to a converting adaptor of 20mm${\Phi}$ coaxial tube from a Type-N connector to 20mm${\Phi}$ coaxial tube and to use it for designing microwave absorber and evaluating absorbing characteristics. Furthermore the measurements of absorbing characteristics and material constants have performed and reviewed which were carried out by using the coaxial tube in the short type and by using rectangular waveguide respectively As a result the validity of the measured values have been confirmed.

• Journal of the Korean Home Economics Association
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• v.24 no.4
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• pp.93-104
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• 1986

The purpose of this study was to see that how about the related variables influence on the use of the microwave oven and how about the use of the microwave oven influence on the time spent in meal preparation and meal management. Questionaires were give to randomly selected homaker's, in kwangju in August, 1986. Data from the 149 response were analyzed according to multiple regression. The results were as follows; 1. The variables affecting the use of the microwave oven were family income, homaker's employed hours, homakers' education level, a period of use a microwave oven, congnition of a special character in a microwave oven, family style of participation in meal preparation, frequency in use of instant food. 2. The variables of the use the microwave oven was significantly influence on the time spent in meal preparation. 3. The variables of the use the microwave oven was not significantly influence on meal management.

• Journal of electromagnetic engineering and science
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• v.6 no.3
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• pp.189-195
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• 2006

In this paper, the derivation of the protection ratio for the digital microwave system with diversity is newly suggested for a basic guidance of initial planning for frequency coordination, and computational results are presented for an actual radio frequency band. The net filter discrimination has been also examined to see the effect of the adjacent channel protection ratio caused by adjacent channel interference. In addition, the protection ratios for the space or frequency diversity system are analyzed in terms of diversity improvement factors to find out an equivalent allowable noise-to-interference ratio (N/I) from degraded fade margin. According to results for 6.2 GHz system, with the space diversity of 25 m distance between antennas or the frequency diversity of ${\Delta}f/f=0.05$, under 64-QAM and 60 km at BER $10^{-6}$, the protection ratio can be greatly reduced in comparison to the non-diversity system. So, assuming that only the same protection ratio as the non-diversity system is kept, it is shown that the system with diversity may get more interference level of N/I allowing from 9.0 to - 5.9 dB or from 6.0 to - 4.3 dB for the space or frequency diversity. In consequence, it is concluded that the diversity system is more robust or tolerable for interferences or fades, which may play an important role in overcoming N/I to some extent.