00823643 - APPLICATION OF RESISTIVE SENSORS FOR SHORT...

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APPLICATION OF RESISTIVE SENSORS FOR SHORT HIGH-POWER MICROWAVE PULSE MEASUREMENT M. Dagys, 2. Kancleris, R. Simni-kis, E. Schamiloglu,+ F.J. Ageel Semiconductor Physics Institute, A. Go-tauto 1 1, Vilnius, 2600, Lithuania Abstract A resistive sensor for nanosecond duration high-power microwave pulse measurement has been designed and tested. It was demonstrated that the sensor can detect about 60 dB greater pulsed microwave power compared with diodes, is resistant to larger power overloads, produces high output signals, and is sufficiently fast to measure nanosecond duration microwave pulses. I. INTRODUCTION At present, short high-power microwave (HPM) pulses in the range of a few tens of nanoseconds are employed in a variety of experiments. Since HPM generators typically operate in the single-shot regime, calibrated diodes are usually used to measure radiated power. These diodes can handle only low power levels; therefore in order to measure HPM pulses the signal has to be strongly attenuated. Large attenuation of HPM power results in a decrease in measurement accuracy. In addition, the diodes produce small output signals and some problems can arise when measuring small DC pulses in the presence of stray pick-up and electromagnetic interference that is typical in the environment of HPM sources. Therefore, a problem of great importance is to develop sensors that can detect HPM pulses directly without attenuation while producing large output signals. In this paper we present resistive sensors (RSs) designed for nanosecond duration HPM pulse monitoring at X-band. The dependence of the output signal on microwave power, and the frequency and time response of the RS have been investigated. The RS has been tested under operating conditions using HPM pulses. . 11. RESISTIVE SENSOR The RS is a short section of standard waveguide (Fig. 1) where a sensor that converts the microwave pulse to a DC pulse is inserted. A. Principle of Operation The performance of the RS is based on the electron heating effect in semiconductors [I]. Briefly it can be explained in the following manner. The electric field of the microwave pulse heats electrons in the sensor; the resistance of the semiconductor subsequently increases. If the duration of the pulse is not too long, andlor the specific resistance of the semiconductor is chosen high enough, the increase of the lattice temperature during the pulse can be made sufficiently small. Thus, by measuring the resistance change of the sensor the microwave pulse power in the waveguide can be determined. The sensor is made from a rectangular bar of n-type Si with Ohmic contacts on its ends. As one can see from Fig. 1 it is placed between the broad wall of the waveguide and a thin metal foil that is located in the waveguide’s H- plane. The sensor’s thickness corresponds roughly to 1/10 of the waveguide’s narrow dimension.
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00823643 - APPLICATION OF RESISTIVE SENSORS FOR SHORT...

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