• 한국전자파학회논문지
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• 제28권11호
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• pp.928-931
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• 2017

본 논문에서는 지표투과레이다용 2 GHz 대역 고효율 펄스발생기의 설계 및 측정결과에 대하여 기술하였다. 기존의 분산증폭기 기반 펄스 발생기의 입출력 정합특성을 개선하기 위해 $90^{\circ}$ 하이브리드 커플러를 이용한 평형 구조를 응용해 설계하였다. 설계된 펄스발생기는 PCB 공정을 이용하여 제작하였다. 펄스 발생기는 5 V 전원 공급 장치에서 약 1 mA 전류를 소모하며, 27.6 %의 전력 효율을 가진다. 출력 전압 진폭은 100 MHz의 PRF(Pulse Repetition Frequency: 펄스 반복 주파수)에서 $3.7V_{pp}$이다. 펄스의 폭은 약 2 ns이며 1.7~2.6 GHz의 동작 주파수에서 입출력 반사손실은 10 dB 이상이다.

• 설비공학논문집
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• 제16권11호
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• pp.1051-1059
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• 2004

Two phase thermosyphone loop for electronics cooling are designed and manufactured to test its performance under the partial load and low environment temperature conditions. The thermosyphone device has six evaporators connected parallel for the purpose of cooling six power amplifier units (PAU) independently. The heater modules for simulating PAUs are adhered with thermal pad to the evaporator plates to reduce the contact resistance. There are unbalanced distributions of liquid refrigerant in the differently heated evaporators due to the vapor pressure difference. To reduce the vapor pressure differences caused by partial heating, two evaporators are connected each other using the copper tube. The pressure regulation tube successfully reduces these unbalances and it is good candidates for a field distributed systems. Under the low environment temperature operating condition, such as $-30^{\circ}C$, there may be unexpected subcooling in condenser. It leads the very low saturation pressure, and under this condition there exists explosive boiling in evaporator. The abrupt pressure rise due to the explosive boiling inhibits the supplement of liquid refrigerant to the evaporator for continuous cooling. Finally the cooling cycle will be broken. For the normal circulation of refrigerant there may be an optimum cooling air flow rate in condenser to adjust the given heat load.