• Journal of Industrial Technology
• /
• v.25 no.B
• /
• pp.175-182
• /
• 2005

This paper presents a LTCC Balun-BPF, which is a BPF(band pass filter) with a Balun in a single LTCC chip for the direct interface with a MMIC chip having balanced inputs. The physical dimension of the designed Balun-BPF is $2.4{\times}2.0{\times}0.88mm^3$ and the used dielectric constant ${\varepsilon}_r$ is 36. A Balun of three-lines structure with striplines and a BPF of comb-line structure was combined into the Balun-BPF. The simulated result shows 4.8㏈ of insertion loss, 178~179 degree of the phase imbalance, 14㏈ of the return.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2002.05a
• /
• pp.227-229
• /
• 2002

In this paper, we report on a microstrip line voltage controlled tunable bandpass filter. We used the characteristic the relative dielectric constant of thin film ferroelectrics depends on the applied dr voltage. we designed using Au/BSTO/MgO/Au structure. We cascaded many resonators for large furling range sustaining 1 GHz renter frequency, narrow band, low IL ($\leq$4 dB). We could design the BPF of which center frequency is 16 GHz, 1.9 GHz tuning range, the narrow bandwidth within 800 MHz, low insertion loss less than 3 dB by adjusting the gap of 3 cascaded resonators.

• Korean Journal of Materials Research
• /
• v.4 no.3
• /
• pp.312-318
• /
• 1994

In this paper the breakdown and dielectric characteristics of purified transformer oil dissolved with $SF_6$ Gas are investigated with a few decade MHz frequency voltage. The results are as follows. 1) High frequency current is a approximately proportional to the square root of high frequency voltage in purified transformer oil. 2) As frequency increase breakdown voltage decrease inversely proportional to the square root of frequency and the high frequency breakdown voltage is lower about 35 percentage than that of AC 3) The breakdown voltage of high frequency has a little increase with the pressure increase of dissolved $SF_6$, Air and Ar Gas. 4) As voltage freguency increases the value of the dielectric loss tangent has increased almost exponentially and the dielectric constant ($\varepsilon$) has tended to decrease with a slope[0.6% MHz]. 5) When dissolved with $SF_6$ Gas, oil electrical characteristics has more increased about 25% than in Air or Ar gas with high voltage frequency.

• Journal of the Korean Ceramic Society
• /
• v.41 no.9
• /
• pp.709-714
• /
• 2004

The additive of low temperature sintering in Mn-doped PMN-PZT known as high piezoelectric materials was studied in this experiment. B$_2$O$_3$ was used for the additive of low temperature sintering. The effects of sintering temperature in dielectric, and piezoelectric properties were investigated with the amounts of B$_2$O$_3$. Sintered density was increased in comparison with no addition and under 2wt％ B$_2$O$_3$ and lower sintering temperature than 100$0^{\circ}C$. Therefore, in the low sintering temperature, the densification was improved by the addition of the B$_2$O$_3$. However, the sintering density was lower than that of the main composition in the case of the sintered at over 10$50^{\circ}C$. Dielectric constant with the addition of B$_2$O$_3$ was evaluated. The dielectric constant was 1000 2 wt％ of B$_2$O$_3$ and sintered at 100$0^{\circ}C$. Under 2wt％ of B$_2$O$_3$, the electromechanical coupling factor and the piezoelectric constant were not so much decreased. The electromechanical coupling factor and the piezoelectric constant were 50％ and 300(${\times}$10$^{-12}$ C/N) respectively. The mechanical quality factor was increased with B$_2$O$_3$. The mechanical quality factor was 1700 at 0.5wt％ B$_2$O$_3$ and sintered at 110$0^{\circ}C$. Dielectric loss was less than 0.5％ regardless of the amount of B$_2$O$_3$.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.18 no.1
• /
• pp.159-165
• /
• 2018

In this paper, a low-loss wideband waveguide transducer is proposed for millimeter-wave communication and radar applications. A conventional E-plane probe transducer is generally designed using thin and flexible substrate at millimeter-wave frequencies, considering the very small waveguide size. However, it results in serious performance degradation caused by the bending of the substrate. In order to alleviate this problem and provide a reliable performance, we propose an extended E-plane probe transducer where the probe substrate is extended to and fix ed in the slit area formed in the waveguide wall. It is fabricated using $127{\mu}m$-thick substrate with dielectric constant of 2.2. The measurement in the back-to-hack configuration shows the excellent insertion loss of 1.35 dB (${\pm}0.35dB$) including the loss of 3 cm-long thru waveguide and return loss better than 13.8 dB over entire W-band (75-110 GHz). Therefore, it can be effectively applied for millimeter-wave high-speed communications and high-sensitivity radars.

• Proceedings of the KIEE Conference
• /
• 1994.11a
• /
• pp.215-218
• /
• 1994

Dielectric properties of $(Sr_{l-x}{\cdot}Ca_x)_mTiO_3+0.006Nb_2O_5$($0.05{\leq}x{\leq}0.2$, 0.996$N_2$) were painted on the surface with CuO paste, and then annealed at $1100^{\circ}C$ for 2hr. Grain size increased with increasing substitutional contents of Ca up to 15[mol%], but decreased with further substitution. In the specimens with $10{\sim}15[mol%]$ of Ca and m=1, excellent dielectric properties were obtained as follows; dielectric constant <25000, dielectric loss($tan{\delta}[%]$) <0.3[%] and capacitance change rate with temperature <${\pm}10[%]$, respectively. All the specimens in this study exhibited dielectric relaxation with frequency as a function of the temperature. The dispersive frequency was over $10^6[Hz]$.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.18 no.4
• /
• pp.587-594
• /
• 2023

In this paper, we present the design and optimization process of an on-body microstrip patch antenna with a paired T-type defect for monitoring fracture recovery of human legs. This antenna is designed to be light, thin and compact despite the improvement of return loss and bandwidth performance by adjusting the size of the T-type defect. The structure around the applied human leg is structured as a 5-layer dielectric plane, and the complex dielectric constant of each layer is calculated using the 4-pole Cole-Cole model parameters. In a normal case without bone fracture, the return loss of the on-body antenna is -66.71dB at 4.0196GHz, and the return loss difference ΔS₁₁ is 37.95dB when the gallus layer have a length of 10.0mm, width of 1.0mme, and height of 2.0mm. A 3'rd degree polynomial is presented to predict the height of the gallus layer for the change in return loss, and the polynomial has a very high prediction suitability as RSS = 1.4751, R² = 0.9988246, P-value = 0.0001841.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.34 no.6
• /
• pp.442-448
• /
• 2021

In this work, the (K_1-xAg_x)(Ta_0.8Nb_0.2)O₃ (x=0.1-0.4) ceramics were fabricated using mixed-oxide method, and their structural and electrical properties were measured. All specimens represented a pseudo cubic structure with the lattice constant of 0.3989 nm. When 0.4 mol of Ag was added, second phases induced from metallic Ag and K₂(Ta,Nb)₆O₁₆ phase were observed. Dielectric constant and dielectric loss of K(Ta_0.8Nb_0.2)O₃ specimen doped with 0.3 mol of Ag were 2,737 and 0.446, respectively. The curie temperature was about -5℃, which does not change with Ag addition. The remanent polarization began to decrease sharply around 12~15℃, and the temperature at which the remanent polarization began to decrease as the applied voltage increased shifted to the high temperature side. The electrocaloric effect (ΔT) and electrocaloric efficiency (ΔT/ΔE) of the (K_0.7Ag_0.3)(Ta_0.8Nb_0.2)O₃ ceramics were 0.01024℃ and 0.01825 KmV^-1, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.27 no.1
• /
• pp.14-17
• /
• 2014

In this study, lead-free Piezoelectric $(Na_{0.47}K_{0.47}Sr_{0.03}Ca_{0.03})(Nb_{0.94}Ti_{0.06})O_3$-0.1 $MnO_2$ ceramics were fabricated using mixed oxide method and the effects of various sintering temperature on the structural and electrical properties were investigated. For the $(Na_{0.47}K_{0.47}Sr_{0.03}Ca_{0.03})(Nb_{0.94}Ti_{0.06})O_3$-0.1 $MnO_2$ (NKN-SCT-$MnO_2$) ceramics sintered at temperatures of $1,025{\sim}1,100^{\circ}C$. The results indicated that all specimens were perovskite single phase formation without any second phase. It has been shown that relative density is increased to increasing sintering temperature. When the sintered temperature at $1,075^{\circ}C$, highest sintered density and maximum value of $4.45g/cm^3$. Average grain size is increased to increasing sintering temperature. The electromechanical coupling factor, dielectric constant, dielectric loss, d33 and curie temperature at the sintering temperature $1,075^{\circ}C$ of NKN-SCT-$MnO_2$ specimens were 0.22, 511, 0.033, 103 and $380^{\circ}C$, respectively.

• Nuclear Engineering and Technology
• /
• v.6 no.1
• /
• pp.14-22
• /
• 1974

Effects of anodization voltage on frequency characteristics of anodic oxide films on tantalum were analyzed based on the following impedance equatious : (equation omitted) Here $R_{f}$, $C_{f}$ and tan $\delta$$_{f}$ are equivalent series resistance in ohm, equivalent Belies capacitance in farad and dielectric loss, of anodic oxide films respectively Parameters P, $\tau$$_{ο}$, $\tau$$_{\omega}$, and Co are defined as follows: P=(d-w)/w, $\tau$$_{ο}$=$textsc{k}$$\rho$$_{ο}$, $\tau$$_{\omega}$=$textsc{k}$$\rho$$_{\omega}$, $C_{ο}$=$textsc{k}$A/d where d is the thickness of oxide film, $\omega$ is the diffusion layer thickness. $\rho$$_{ο}$ is the resistivity of oxide film at the interface of metal and the oxide, $\rho$$_{\omega}$ is the resistivity of oxide film at intrinsic region and A is the area of the film and $textsc{k}$=0.0885$\times$10$^{-12}$ $\times$dielectric constant, (in farad/cm). It was shown that dielectric loss and frequency dependence of equivalent series capacitance decrease as anodization voltage increases. This is a consequence of the fact that the thickness of diffusion layer increases a little with increasing anodization voltage whereas the total oxide thickness is proportional to the anodization voltage. The ngative deviation of measured values from tile relation, tan $\delta$$_{f}$=0.682 $\Delta$ $C_{f}$, was also discussed based on the Impedance equations given above. Here $\Delta$ $C_{f}$ is the change in capacitance between 0.1 and 1 KHZ.KHZ.Z.