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RECENT ADVANCES IN HPM PULSE MEASUREMENT USING RESISTIVE SENSORS& 2. Kancleris*, M. Dagys, R SimniSkis, E. Schamilogld, F. J. Agees Semiconductor Physics Institute, A. Goffuufo I I Vilnius, 2600, Lithuania Abstract The resistive sensor (RS), whose performance is based on the electron heating effect in semiconductors, has found application in high-power microwave (HpM) measurements. Our previous studies concentrating on the waveguide-type RS have demonstrated their advantages over conventional diodes that are also used to measure HPM pulses [l]. The RS can detect ahout 60 dB greater power level, are resistant to large power overloads and demonstrate very good long-term stability. They can produce an output signal on the order of a few tens of volts without any amplification circuit and can resolve nanosecond duration HPM pulses. In this paper we present a brief overview of the waveguide-type RS as well as a survey of recent advances in the RS design. I. RESISTIVE SENSOR The performance of the RS is based on the well-known electron heating phenomenon in semiconductors. When strong electric field pulse is applied to a semiconductor, a new steady state of the electron system is established with mean electron energy much greater than the equilibrium energy. Heated electrons, as a tule, are scattered more frequently hy the lattice imperfections and the resistance of a semiconductor in a strong electric field increases. This effect is used for microwave pulse power measurement. A bar-shaped piece of n-type Si with Ohmic contacts on the end is inserted in a transmission line (usually waveguide). The microwave electric field heats the electrons in the sensor, and its resistance thereby increases; by measuring this resistance change microwave pulse power in the transmission line is determined. A DC current source or a DC pulse synchronized with the pulse being measured is used to measure the change of the resistance of the RS [ 11. In the latter case the output signal of a few tens of volts is detected without any amplification. 11. WAVEGUIDE-TYPE RS A sketch of the waveguide-type RS used for HPM pulse measurements is shown in Fig. 1. It is seen that the RS is designed as a standard waveguide section with a sensing element mounted under a thin metal diaphragm that is parallel to the broad wall of the waveguide. The height of the sensing element roughly corresponds to 1/10 of the waveguide’s narrow dimension. Two modifications of the RS for various dimensions of the waveguide in the frequency range 1-37.5 GHz have been designed and manufactured. The fust one is devoted to detect HPM pulses with duration in the range 0.5-300 ps [2]. The other modification of the FS with improved response time was used to measure nanosecond duration HPM pulses [3]. Both types of the RS have been tested under working
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This note was uploaded on 06/07/2011 for the course EE 11 taught by Professor D during the Spring '11 term at Central Lancashire.

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