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Content available remote Detektor mikrofalowy ze wzmacniaczem wizyjnym
PL
W artykule przedstawiono opis, budowę oraz podstawowe charakterystyki detektora mikrofalowego ze wzmacniaczem wizyjnym. Układ przeznaczony jest do detekcji sygnałów ciągłych i impulsowych w paśmie częstotliwości 750-2000 MHz. Był opracowywany na potrzeby budowy stanowiska do monitorowania emisji mikrofalowych.
EN
The microwave detector is the essential element of many receiving systems. Microwave detectors are used to convert the signals power into DC voltage. The power range of the receiving signals is very wide. In some cases, the level of signals after detection might be very low, so the video amplifier application is necessary. In the paper, the microwave detector with a video amplifier has been described. The presented detector will be used in the system being designed for monitoring of electromagnetic environment. In such application, very important parameters of the microwave detectors are matching and voltage sensitivity. It is very difficult to achieve the enough good and constant value of the voltage sensitivity over the wide frequency band. The worked out microwave detector with a video amplifier is very good matched, has relatively high sensitivity and can be connected to measurement devices with both small and large input impedance. Magnitude of reflection coefficient is better than -22 dB, average voltage sensitivity is of about –2.5 mV/µW regardless of loading resistance, noise level is not more than 1.5 mVpp. Detector with a video amplifier can determine the envelope of CW microwave signals and microwave pulses not shorter than 0.3 µs. A complete instrument is mounted in a small handy case.
2
Content available remote Properties of constricted 2DEG/metal structures in microwave electric fields
EN
Detection properties of asymmetrically constricted 2DEG/metaI junctions were investigated at 10 GHz frequency at room and liquid nitrogen temperature. Operation of such detectors is based on non-uniform carrier heating in the constricted region. Different quality of the 2DEG channel was obtained for AlGaAs/GaAs modulation doped heterostructures with superlattice buffer structure and without it. Photoluminescence measurements exhibited effective charge accumulation in the AlGaAs/GaAs potential channel in the case of superlattice buffered structure, while in the non-buffered structure a substantial portion of excited carriers recombined in doped AlGaAs layer. The quality of the 2DEG channel was responsible for different polarity of the detected voltage as well as for different voltage sensitivity; in the case of the non-buffered structure the sensitivity reached almost 200 V/W value.
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