• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.1
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• pp.81-85
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• 1996

Microwave dielectric properties of 0.15(B $a_{x}$S $r_{0.05}$)O-0.15(S $m_{2}$(1-y)N $d_{2y}$) $O_{3}$-0.7Ti $o_{2}$(x=o.9~0.1[mol.], y=6[m/o]) ceramics were investigated with BaO compositional ratio. Sintered density and resistivity of specimens were independent on the BaO compositional ratio. In the specimen with x=0.975[mol.], dielectric constant, quality factor and temperature coefficient of resonant frequency had good values of 76.52, 3001(at 3[GHz]) and +0.71[ppm/.ceg. C], respectively. By comparing with the stoichiometric compositions of 78.14, 2938(at 3[GHz])+14.19[ppm/.ceg. C], dielectric constant and quality factor showed similar properties, but the temperature coefficient of resonant frequency was highly improved. (author). refs., figs., tabs.s.s.

• Electrical & Electronic Materials
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• v.9 no.5
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• pp.439-444
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• 1996

0.15(B $a_{0.95}$ S $r_{0.05}$)O-0.15(S $m_{2(1-x}$/N $d_{2x}$) $O_{3}$-0.7Ti $O_{2}$(x=0-10[m/o]) ceramics were fabricated by mixed oxide method. Microwave dielectric properties were investigated with contents of N $d_{2}$ $O_{3}$. In the case of specimen with N $d_{2}$ $O_{3}$(6[m/o]), dielectric constant, quality factor and temperature coefficient of resonant frequency were 78.14, 2938(at 3[GHz]) and +14.19[ppm/.deg. C], respectively. By comparison its properties with undoped specimen, dielectric constant and quality factor were highly improved, but the temperature coefficient of resonant frequency was increased to positive value......

• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.1
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• pp.23-30
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• 2007

We observed the NaCl concentration of solutions using a near-field microwave microprobe(NFMM). Instead of the usual technique, we take advantage of the noncontact evaluation capabilities of a NFMM. A NFMM with a high Q dielectric resonator allows observation of small variations of the permittivity due to changes in the NaCl concentration. The changes of NaCl concentration due to a change of permittivity of the NaCl solution were investigated by measuring the microwave reflection coefficient $S_{11}$ of the resonator. The NaCl sensor consisted of a dielectric resonator coupled to a probe tip at an operating frequency of about f=4 GHz. The change of the NaCl concentration is directly related to the change of the reflection coefficient due to a near field electromagnetic interaction between the probe tip and the NaCl solution. In order to determine the probe selectivity, we measured a mixture solution of NaCl and glucose.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.79-82
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• 2003

본 논문은 마이크로파발진기의 위상잡음 특성에 영향을 미치는 P-HEMT의 비선형 파라미터를 선정하고, 3개의 비선형 파라미터와 최소 위상잡음을 분석하였다. 분석된 P-HEMT가 저 위상잡음을 가지는 최적의 바이어스 동작점을 선정하여, 선정된 바이어스 동작점에서 두 가지 형태의 발진기를 설계하므로 서 발진기의 물리적 구조에 의한 위상 잡음의 영향을 비교하고 위상잡음의 감소방안을 제시하였으며, 이를 이용하여 ku-대역 위상동기유전체공진 발진기를 설계 제작하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.1
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• pp.107-114
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• 2021

In this paper, a planar transistor oscillator for X-band using a newly proposed L-shaped monopole slot resonator is proposed. For planar design, an L-shaped monopole slot with an open-end is used as a resonator for a transistor oscillator. As a result of the simulated design of the resonator in three stages, a high Q value of 1169.84 and a high insertion loss of 49.934 dB were identified. The results of the final design and manufactured oscillator measurements confirmed that the oscillation output is greater than 7 dBm and has good phase noise characteristics of -58 dBc/Hz at 100 kHz offset. The proposed oscillator is planar and has the advantage of being directly applicable to microwave integrated circuit technology. It also has the advantage of being able to reduce its size as it can only be implemented in microstrip form without additional devices such as metal cavities and tuning screws in 3D structures, as in the case of a DRO (dielectric resonance oscillator).

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.4
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• pp.243-248
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• 2015

Since phase noise is one of the most important parameters in the design of microwave oscillators, several methods have been proposed to reduce the phase noise. These methods have focused on improving the quality factor of resonators, which result in low phase noise oscillators. Dielectric resonators have been widely used for low phase noise in microwave oscillators due to their high quality factor. However this cannot be used in MMIC oscillators because they have a 3D structure. In this paper, to overcome this problem a novel resonator using open ring type DGS is proposed for improvement of phase noise characteristics that is weak point of oscillator using planar type microstrip line resonator, and oscillator for 5.8GHz band is designed using proposed DGS resonator. The open ring type DGS resonator is composed of DGS cell etched on ground plane under $50{\Omega}$ microstrip line. At the fundamental frequency of 5.8GHz, 6.1dBm output power and -82.7 dBc@100kHz phase noise have been measured for oscillator with ring type DGS resonator. The phase noise characteristics of oscillator is improved about 96.5dB compared to one using the general ${\lambda}/4$ microstrip resonator.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.5
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• pp.863-871
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• 2003

In this paper, we design a high stable Ku-band phase-locked dielectric resonant microwave oscillator with the gate voltage controls of p-HEMT. By adapting the nonlinear equivalent elements which affects phase noise of microwave oscillator, we optimize the nonlinear elements of p-HEMT to have low phase noise operation. Using the scattering parameters according to bias voltages, we designed the gate voltage control microwave dielectric resonant oscillator and phase-locked loop circuits is applied to have the high stable operations. Designed microwave oscillator as a local oscillator of digital microwave communication shows that output power is 9.17dBm at 10.75GHz and it's phase noise is -88dBc/Hz at 10KHz offset frequency.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.4
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• pp.279-285
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• 2017

In this paper, the resonator with a parallel plate capacitor is newly proposed around sub-microwave frequency band and applied to earlobe for non-invasive glucose monitoring the human biological tissue. The capacitor including the earlobe as dielectric material is connected to inductive slot in the ground plane of the microstrip line. Based on the simulation, one port resonator circuit is designed and fabricated as a prototype. Three step glucose concentration levels(0, 250, 500 mg/dL) was tested, and its reflection coefficients($S_{11}$) were measured. Owing to high Q resonator more than 100, resonant frequency shift of about 9 MHz per glucose level of 250 mg/dL has been successfully measured. This proves that the proposed sensor is applicable to a blood glucose sensor.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.2
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• pp.78-85
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• 1998

The design method of a temperature stable bandpass filter using dielectric coaxial resonators of with two dielectric ceramics with opposite signs of temperature coefficient of dielectric constant (${\tau}_{\epsilon}$) to compensate for each other in this method. $MgTiO_3$(${\tau}_{\epsilon}$=+99 ppm/${\circ}C$) as a positive ${\tau}_{\epsilon}$ material and Ba($Zn_{1/3}Nb_{2/3}$)$O_3$(${\tau}_{\epsilon}$=-77ppm/${\circ}C$) as a negative material were selected. The length of a SIR for the temperature stability was calculated according to the design method and the susceptance slope parameter of the SIR was obtained. A temperature stable bandpass filter using dielectric SIR's was designed, simulated and fabricated. The center frequency of this filter was 915 MHz and the pass bandwidth was 20 MHz. Temperature properties of this bandpass filter by simulations were compared with the measured results of the bandpass filter fabricated.

• Journal of Advanced Navigation Technology
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• v.23 no.1
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• pp.69-76
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• 2019

In this paper, a design method for an enhanced-sensitivity microwave sensor based on microstrip defected ground structure was studied for the permittivity measurement of planar dielectric substrates. The proposed sensor was designed by modifying the ridge structure of an H-shaped aperture into the shape of a capacitor symbol. The sensitivity of the proposed sensor was compared with that of a conventional sensor based on a double-ring complementary split ring resonator(DR-CSRR). Two sensors were designed and fabricated on a 0.76-mm-thick RF-35 substrate so that the transmission coefficient would resonate at 1.5 GHz in the absence of the substrate under test. Five types of taconic substrates with a relative permittivity ranging from 2.17 to 10.2 were selected asthe substrate under test. Experiment results show that the sensitivity of the proposed sensor, which is measured by the shift in the resonant frequency of the transmission coefficient, is 1.31 to 1.62 times higher than that of the conventional DR-CSRR-based sensor.