• Proceedings of the KAIS Fall Conference
• /
• 2004.06a
• /
• pp.86-88
• /
• 2004

본 연구에서는 고주파 이동통신 기기용 칩형 세라믹 안테나의 사용을 위한 저유전율 및 저온동시소성이 가능한 CaO-B2O3-SiO2계 유리를 제조하고자 하였다. 제조된 CaO-B2O3-SiO2계 유리는 열분석을 통하여 낮은 연화온도를 갖는 안정한 유리조성을 선정하였다. 유리분말을 이용하여 성형된 샘플은 소결온도에 따른 특성을 조사하였다. 소결온도변화에 따라 유전율(${\epsilon}_r$)은 4-4.5값을 나타냈으며, 유전손실(tan$\delta$)은 <$0.1\%$ 보였으나, 품질계수(Q$\times$f)는 큰 변화폭을 보였다.

• Electrical & Electronic Materials
• /
• v.5 no.1
• /
• pp.28-42
• /
• 1992

본 논문에서는 ZnO 바리스터의 유전특성에 대해 검토하였다. 25~75[.deg.C]의 온도에서 1[kHz]~13[MHz]의 부파수 범위에서 LCR meter와 computer로 구성된 측정장치를 사용하여 정전용량-주파수, 및 손실계수-주파수의 관계를 측정하였다. 수학적 해석 방법에 의해 복소유전율의 실험결과로 부터 3-4개의 Debye 피크를 추출할 수 있었다. 각 피크를 .alpha., .betha., .gamma. 및 .delta.라 할 때 활성화에너지는 각각 0.35-0.48, 0.62-0.99, 0.48 및 0.33-0.41[eV]이었고, 각 피크 중 .gamma.는 공핍층에 형성된 도너준위, .alpha. 및 .delta.는 결정립 계면준위, .betha.피크는 도너이온에 의한 것으로 추정된다.

• Journal of the Microelectronics and Packaging Society
• /
• v.10 no.1
• /
• pp.51-56
• /
• 2003

Microwave dielectric properties of the $MgTiO_3-CaTiO_3$ ceramics were investigated for GPS antenna fabrication. (1-X) $MgTiO_3-X CaTiO_3$ ceramics with X=7 mol% sintered at $1400^{\circ}C$ exhibited can be dielectric constant of 20.6, the quality factor of 52,500 and the temperature coefficient of resonant frequency of -1.5 [ppm/$^{\circ}C$]. The results of $0.93MgTiO_3-0.070CaTiO_3$ ceramics with $P_2O_5$/ 0.6 wt% sintered at $1250^{\circ}C$ exhibited can be dielectric constant of 21, the quality factor of 58,000 and the temperature coefficient of resonant frequency of 2.6 [ppm/${\circ}C$]. The size, insertion loss, center frequency and band width of GPS antenna were $20.5{\times}20.5{\times}6[mm]$,-10(dB) and 1575.42(MHz) respectively. The insertion loss, center frequency and band width of the fabricated GPS antenna were -11 (dB), 1579(MHz) and 22(MHz) respectively. The center frequency was higher than design result, but other characteristics of GPS antenna were similar to the results of design result.

• Journal of the Microelectronics and Packaging Society
• /
• v.26 no.4
• /
• pp.69-74
• /
• 2019

The influence of measuring fixtures on the measurement of dielectric and piezoelectric properties of PMN-PT single crystal specimens was investigated. As the pressure of the jig pin which applied the AC electrical signal to the sample decreased, the lower resonance resistance was measured and the higher mechanical quality factor was calculated. The mechanical quality factor was 418 when the spring tension of the jig pin was 20grf, and the value of the quality factor was reduced by half when the spring tension was 200grf. The 4-probe fixture method is unsuitable for measuring piezoelectric properties, but it was suitable for the measurement of dielectric loss. In order to accurately evaluate the piezoelectric properties of PMN-PT, it is necessary to lower the spring tension of the jig pin as much as possible.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.42 no.1
• /
• pp.39-45
• /
• 2005

As a basic research for the development of a non-invasive blood glucose sensor using millimeter waves, we have presented a method for measuring the dielectric properties of high loss dielectrics, based on the reflection method, and investigated the variation of the dielectric properties of glucose-water and glucose -0.9% NaCl solutions in the 10～90 GHz range. In the proposed method, a minimal reflection condition is formed by placing a specially-chosen low-loss plane-parallel plate in front of a high-loss medium under test at a given frequency range. Using the minimal power reflection coefficient and the corresponding frequency at this condition, tile dielectric properties of the medium can be determined. The measured results on pure water have shown the adequacy of the proposed method. The measured results on glucose-water and glucose -0.9% NaCl solutions in the 10～90 GHz range showed that the variations of the dielectric properties of glucose solutions according to the change of their glucose concentration were maximum in the 30～45 GHz range. From these facts we concluded that the variation of about 3 mole/L in the glucose solutions must be distinguished With the measurement accuracies of ±0.1 dB and ±0.01 GHz.

• Korean Journal of Food Science and Technology
• /
• v.31 no.1
• /
• pp.122-127
• /
• 1999

Quality changes of Korean ginseng on microwave drying were determined in terms of water activity, crude protein, crude lipid, crude ash, dielectric properties, content of sugar, ginsenoside composion, microstructure. Korean fresh ginseng were subjected to four different processing : 3 min microwave drying and 2 min holding-24 hrs drying (MWI), 5 min microwave drying and 2.5 min holding-24 hrs drying (MW2), 3 min microwave drying and 2 min holding-12 hrs after hot air drying for 12 hrs drying at $45^{\circ}C$ (MWH1), 5 min microwave drying and 2.5 min holding-12 hrs drying after hot air drying for 12 hrs at $45^{\circ}C$ (MWH2), Water content was decreased 14.33% without shrinkage and water activity was 0.57 after microwave drying. Permittivity was increased as water content increased. As temperature increased, permittivity was increased until $40^{\circ}C$ and fast decreased over $40^{\circ}C$. Content of ginsenoside for MW1 and MW2 was higher than that of MWH1 and MWH2. Data of free sugar showed that there was no significant difference in each treatment. The MW2 dried ginseng showed a more compact structure than the MWH2 ginseng.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.20 no.9
• /
• pp.936-942
• /
• 2009

This paper presents the delivered power and reflection coefficient in metallic shielding enclosure with a sub-cavity, which are evaluated with the method of moments, sad describes a method for controlling the resonance characteristics of the metallic cavity by putting lossy dielectric material in the sub-cavity. In this paper we introduce carbon polystyrene-foam as lossy dielectric material and observe it's effects of reduction when the dimensions of the sub-cavity and permittivity of lossy dielectric material are changed. The results show that the reduction of the electromagnetic radiation can be achieved by controlling the amount of carbon in lossy dielectric material and the dimensions of the sub-cavity. The theoretical analysis is verified by the measured delivered power.

• Korean Journal of Materials Research
• /
• v.2 no.4
• /
• pp.263-269
• /
• 1992

Low-firing dielectric materials with negative small temperature coefficients were investigated. The newly developed materials are based on Ti$O_2$(100-x)/ CuOx(X=1~5wt%) with small amount of Mn$O_2$ additive. The sample without CuO was not sintered at 90$0^{\circ}C$. As CuO content was increased the sample could be sintered at low temperature. However, the dielectric constant was decreased and the dielectric loss was increased. In the case of adding 3wt% CuO and 0.6wt% Mn$O_2$, the dielectric constant and the Q values appeared very high.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2000.11a
• /
• pp.238-242
• /
• 2000

In this paper, the method for dielectric constant and less tangent measurements of microwave substrates using a microstrip line is presented. The two samples of an open-ended line and a short-ended tine are made and complex propagation constant is evaluated from the one-port scattering parameter measurements. This method has been automated fully using a personal computer and a vector network analyzer.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2001.11a
• /
• pp.231-234
• /
• 2001

위성방송 수신을 위한 S-band용 LNB를 유전율3.48, 기판두께 0.762mm의 기판을 사용하여 NF=0.9 dB, 변환이득 56dB, Gain Flatness +0.7dB/27MHz을 만족하도록 설계하였으며 대역통과필터는 원하는 대역내에서 삽입손실 -2dB, 반사계수 -l2dB 이하의 결과를 얻었다. 발진기는 3.62GHz에서 6.17dBm의 출력을 나타내었으며 위상잡음은 중심주파수 3.62GHz의 100kHz offset 지점에서 -98 dBc/Hz의 특성을 얻었다.