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

• The Transactions of the Korean Institute of Power Electronics
• /
• v.7 no.1
• /
• pp.48-54
• /
• 2002

This paper is described the indirect induction heated boiler and induction heated hot air producer using the voltage-fed series resonant high-frequency inverter which can operate in the frequency range from 20 kHz to 50 kHz. A specially designed induction heater is composed of laminated stainless plates, which have many tiny holes and are interconnected by spot welding. This heater is inserted into the ceramic type vessel with external working coil. This working coil is connected to the inverter and turbulence fluid through this induction heater to moving fluid generates in the vessel. The operating performances of this unique appliance in next generation and its effectiveness are evaluated and discussed from a practical point of view.

• Proceedings of the KIEE Conference
• /
• 2002.07b
• /
• pp.1043-1045
• /
• 2002

고전압 전원공급기를 고 밀도로 제작하기 위하여 고 주파수 동작을 시켜야 한다. 이에 따라 전원 공급기에서 최대의 부피를 차지하는 부품인 변압기는 원하는 주파수에서 최소의 부피로 충분한 전력을 수용하면서 완벽한 펄스재현을 하여야 한다. 고전압 전원공급기는 풀-브릿지 DC/DC 컨버트로 구성되어 있으며 스윗칭 주파수는 100 kHz 이다. 변압기는 일차권선이 1개이며 이차 권선은 4개로 구성된다 일차전압은 250 Vdc, 이차 권선 각각의 출력은 520 Vrms이다. 변압의 이차 권선은 배 전압 회로를 이용하여 승압 후 각각을 직렬로 연결하여 -4,100 VDC와 -2,050 VDC를 만들어 TWT(Travel Wave Tube)의 케소드 및 콜렉트에 공급한다. 이 변압기는 100 kHz 펄스로 동작하고 최대부피가 400$cm^3$이하가 되어야 한다. 본 논문에서는 이러한 변압기의 설계 방법 및 최소 온도상승을 위한 적절한 동작 자속밀도의 선택에 대하여 기술하고 변압기의 누설 인덕턴스, 분포 케페시턴스, 공진 주파수에 대하여 설계치 및 실험치를 비교 평가하였다.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.4
• /
• pp.740-746
• /
• 2009

Two step serial load induction superheater has been proposed using resonance type induction heat method in this paper. Heat method is a type of flowing the electron induction and current to special alloy heater in body from external heat coil with non-contact method. Inverter was a full bridge serial load resonance type and inductor was used as load in LC resonance design to maximize the efficiency. The developed system is a new heat exchanging method combined with electromagnetic induction heater and fluid movement, ana very accurate to control of heating the gas, liquid and evaporated mass, so on without combustion process.

• Journal of IKEEE
• /
• v.15 no.1
• /
• pp.49-56
• /
• 2011

In this paper, a compact doppler sensor with oscillator type active antenna operating at 2.4GHz frequency band is proposed to measure the distance or speed of a moving object. The active antenna has been realized by oscillator using radiator, patch antenna, as its resonator. The oscillation frequency is shifted depending on approaching of the object, and a detection circuit discriminates the frequency deviation. The oscillator type active antenna has been designed and simulated. The prototype fabricated has a very small circular disk type of diameter 30mm and height 4.2mm. As for antenna performance, broadside radiation pattern with beamwidth of $130^{\circ}$ and oscillation frequency of 2.373GHz has been measured. Test results as a doppler sensor shows that doppler signal voltage of about 190mV has been obtained for conducting plate moving 1 meter away from the sensor. And, doppler signal voltage has been linearly increased to the ground from 4.5m height by free-falling the sensor.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.18 no.3 s.118
• /
• pp.315-322
• /
• 2007

In this paper, active integrated antenna with left hand circular polarization(LHCP) for a transmitter of UHF RFID reader has been described. A novel rectangular ring patch as a radiator of the active antenna is proposed for easier impedance matching, smaller patch size, and LHCP characteristics. An amplification circuit is placed in the opening area of the radiator and is combined with it to work as oscillating circuit around 915 MHz. From the test results, impedance bandwidth of 29 MHz, 3 dB axial ratio bandwidth of 20 MHz, 3 dB beamwidth of 85 degree, and effective radiation power of 8.8 dBm have been obtained.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.47 no.2
• /
• pp.62-66
• /
• 2010

In this article, a oscillator at X-band with a double H-shape metamaterial resonator (DHMR) based on high-Q is proposed with metamaterial structure to improve Ihe phase noise and output power. The proposed oscillator is required low phase noise and high output power for the high performance frequency synthesizer. DHMR is designed to be high-Q at resonance frequency through strong coupling of E-field. This character makes phase noise excellent. The oscillator using DHMR is oscillated in X-band so as to apply frequency synthesizer of radar systems. The output power is 4.33 dBm and the phase noise is -108 dBc/Hz at 100 kHz offset of carrier frequency.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.12 no.1
• /
• pp.56-64
• /
• 2007

Recently, the high frequency link boost DC/DC converter has been used widely for PCS (Power Conditioning System) because of the requirements of small size and low cost. However, the high frequency link boost DC/DC converters applied the conventional voltage-fed converter and current-fed converter have some problems like high conduction losses and high surge voltage due to high circulating current and leakage inductance, respectively. To improve these problems, a novel secondary LLC (called SLLC) series resonant converter is proposed in this paper and its theoretical analysis, its operating waveforms, simulation and experimental results for a boost DC/DC converter using SLLC series resonant topology verifies the proposed topology. 800W experimental prototype is tested.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1995.10a
• /
• pp.74-79
• /
• 1995

모우드 밀도의 산정을 정확하게 구하기 위해 고주파수 영역에서 흔히 적용되는 3채널 측정법이 저주파수대 영역에서도 2채널법에 의한 방법보다 주파수 응답함수의 크기 및 공전주파수의 위치를 보다 더 잘 나타내 주고 있다는 것을 실험적으로 제시하였다. 2채널 측정법에 비하여 3채널 측정법이 모우드 밀도가 균일한 보의 경우에 있어서도 주파수 응답함수의 크기를 실제의 경우와 근접하게 추정해 줄 수 있을 뿐 아니라, 상대적으로 모우드 밀도가 높은 평판의 경우에 있어서도 공진주파수 대에서의 주파수 응답함수의 형태를 보다 분명히 나타내어 줄 수 있는 것으로 나타났다. 한편, 구조물과 가진기의 상호작용에 의한 고유진동수의 변동량 측정의 관점에서는 2채널 측정법과 3채널 측정법의 경우 모두 주파수 응답함수를 적절히 나타내어 주고 있는 것으로 나타났다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.19 no.10
• /
• pp.1104-1114
• /
• 2008

In the output of a mixer, spurious appears with the desired signal, and a filter is necessary to suppress the spurious. In this paper, the planar filter for Ka-band frequency synthesizer was designed and fabricated. In this procedure, the frequency response becomes asymmetric because of discontinuities at the high frequency. Using this, we designed short-end PCLF by using a individual resonator tuning method. The fabricated 5th-order Ka-band pass filter is compared with the result of EM simulation through measurement. The performance agrees with the simulation. Finally spurious suppression was examined through the measurement of output spectrum of the mixer with the filter.