• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.5
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• pp.559-575
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• 2014

In this paper, we propose a horizontal/vertical calibration kit for calibrating a vector network analyzer(VNA) to measure the vertical connector pin. If the conventional calibration kit is used, we should change the arm for a probe or need an assistant device and it takes a long time. In addition there is a risk of precision degradation caused by the position change of the probe tip sensitive to the surroundings. We suggest a 4-port vertical calibration kit to make up for the aforementioned shortcomings. The calibration kit was manufactured for the SOLT calibration method. 'Short', 'Open', and 'Load' are available in the horizontal plane, 'Thru' is available not only in the horizontal plane on the two planes of a PCB, but in the vertical plane between the two planes according to the positions of the probes. We complemented the conventional calibration kit to make a vertical calibration kit to be used for the vertical measurement method. We compared and analysed their reflection/transfer characteristics of the SOLT calibration standards of the proposed calibration kit and conventional one, we get a ${\pm}0.1$ dB differences of transfer characteristics in the range from 300 kHz to 8.5 GHz. In order to demonstrate usefulness, and we performed a case study for horizontal and vertical cases, and compared the results of the proposed calibration kit and conventional one.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.1
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• pp.76-84
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• 2012

In this paper, two kinds of E-plane microstrip-to-waveguide transitions are optimally designed and fabricated for combining output power from multiple small-power amplifiers in a WR-28 waveguide because conventional K connectors cause unnecessary insertion loss and adaptor loss. The transition design is based on target specifications such as a center frequency of 35 GHz, bandwidth of ${\pm}500MHz$, 0.1 dB insertion loss and 20 dB return loss. Performance variation caused by mechanical tolerance and assembly deviation is fully evaluated by three dimensional electromagnetic simulation. The fabricated back-to-back transitions with 16 mm and 26.57 mm interstage microstrip lines show insertion loss per transition of ~0.1 dB at 35 GHz and average 0.2 dB over full Ka band. Also the back-to-back transition shows return loss greater than 15 dB, which implies that the transition itself has return loss better than 20 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.3 s.106
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• pp.239-248
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• 2006

In this paper, the cryogenically cooled low noise amplifier module for radio telescope receiver front-end using pHE-MT MMIC is designed and fabricated. In the selection of MMIC, the MMIC fabricated with the pHEMTS providing successful cryogenic operation are chosen. They are mounted in the housing using the thin film substrate. In the design of the housing, the absorber and the elimination of the gap between the carrier and the housing as well removed the unnecessary oscillations by its structure. The mismatch is improved by ribbon-tuning to provide the best performance at room temperature. The fabricated module shows the gain of $35dB{\pm}1dB$ and the noise figure of $2.37{\sim}2.57dB$ at room temperature over $21.5{\sim}23.5GHz$. In the cryogenic temperature of $15^{\circ}K$ cooled by He gas, the measured gain was above 35 dB and flatness ${\pm}2dB$ and the noise temperatures of $28{\sim}37^{\circ}K$.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.6
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• pp.41-50
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• 2011

This article is concerned with the technology to provide car driver the car's status which are composed of car trouble code in car engine and many sensors. In addition, it installs vehicle diagnostic programs on wireless communication's portable device, for example, Smart phone, PDA, PMP, UMPC. As a result, this is to provide car manager with many information of car sensors when we go to car maintenance. it can monitor relevant information on vehicle by portable device in real time, alert drivers with specific messages and also enable them to address abnormalities immediately. Moreover, the technology could help the drivers who perhaps don't know very well about their vehicles to drive safely and economically as well; the reason is because the whole system is composed of just Vehicle-information collecting device and personal wireless communication's portables and transfers the relating data to server computers through wireless network in order to handle information on vehicles. This technology make us monitor vehicle's running, failure and disorder by using wireless communication's portable device. Finally, this study system is composed of a lot of application to display us the car's status which get car's inner sensor information while driving a car.