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Wzmacniacz niskoszumny z tranzystorem GaN PolHEMT na pasmo L

Gryglewski D., Góralczyk M., Sokół S.

Przegląd Elektrotechniczny

2015

R. 91, nr 9

36-40

W celu zbadania możliwości realizacji stopni wejściowych odbiorników mikrofalowych z wykorzystaniem technologii azotkowej skonstruowano wzmacniacz niskoszumny (LNA) z tranzystorem GaN HEMT wytworzony w projekcie PolHEMT. Zbudowany wzmacniacz stanowi także element weryfikacji opracowanej technologii GaN HEMT. W referacie opisano metodę modelowania szumowego tranzystora GaN HEMT oraz przedstawiono etapy projektowania wzmacniacza LNA na pasmo 1,1÷1,3 GHz.

In this paper the development of the L-band low noise amplifier with GaN HEMT manufactured by consortium PolHEMT is described. The application of GaN HEMTs in the input stages of radar T/R modukles is very important issue, because the robust of the receivers may be increased as well as the limiters can be eliminated. This LNA is also a verification element of PolHEMT.

Fatigue and ultrasonic testing of epoxy-glass composites

Rojek M., Stabik J., Sokół S.

Journal of Achievements in Materials and Manufacturing Engineering

2007

Vol. 20, nr 1-2

183-186

Purpose: The purpose of this paper was to find relationship between the degree of strength degradation caused by fatigue and the changes of ultrasonic wave characteristics such a wave velocity and damping coefficient. Design/methodology/approach: Epoxy-glass composites were subjected to oscillatory bending loadings with constant deflection. During fatigue procedure the force needed to achieve constant deflection was measured. During fatigue tests samples were subjected to ultrasonic tests. Additionally before fatigue test and after 300 000, 850 000 and 1 900 000 cycles parts of samples were subjected to destructive bending test. Findings: A good correlation between velocity of ultrasonic wave propagation and the degree of strength degradation of epoxy-glass composites caused by fatigue was found. Ultrasounds can be applied as effective tool to assessment of fatigue degradation of polymer composites. Research limitations/implications: Achieved results showed that research have to be continued. Fatigue with other loading conditions and for other composite materials is planned. Practical implications: The results of present research can be applied to elaboration of non-destructive method of measurement of the degree of fatigue degradation of polymer composites. Originality/value: Presented correlation between ultrasound wave characteristics and the degree of strength degradation caused by fatigue is original value of this paper.