04405200 - Proceedings of the 37th European Microwave...

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Resistive Sensor for High Power Millimetre Wave Pulse Measurement Žilvinas Kancleris, Mindaugas Dagys, Rimantas Simniškis and VincasTamoši ū nas Microwave Laboratory, Semiconductor Physics Institute, A. Gošauto 11, Vilnius LT-01108, Lithuania [email protected] Abstract — A high power millimetre wave pulse sensor for 78-118 GHz frequency range has been developed. A finite difference time domain method was applied to optimise the sensor’s frequency response. Two groups of sensors were manufactured and tested experimentally. A voltage standing wave ratio and dependence of the output signal on pulsed power have been measured. The sensor has been tested up to 2 kW pulse power. Dependences of sensitivity on frequency were measured and reasonable agreement between the measured and calculated values has been obtained, once the finite thickness of upper metal contacts of sensing elements and the air gap between them is taken into account. I. INTRODUCTION In recent years, high power microwave (HPM) pulse generation techniques progressed rapidly towards higher frequencies [1]. Thus, new requirements for sensors being used for the measurement of HPM pulses in millimetre wave region are imposed. One of the possible solutions is a resistive sensor (RS), the performance of which is based on electron heating effect in semiconductors. A sensing element of the RS is placed in the waveguide where HPM pulses propagate. Electric field of the pulse heats electrons in the sensing element, its resistance increases and by having measured this resistance change, the power of the HPM pulse in the waveguide is determined. The RS has been successfully applied for the measurement of HPM pulses in centimetre wave region [2]. The following advantages of the RS over the diode can be named basing on the experience gained using the RS in Russian, Swedish and USA laboratories. The RS measures HPM pulses directly, is resistant to large power overloads and demonstrates very good long-term stability. It can resolve nanosecond duration HPM pulses and can produce an output signal of the order of a few tens of volts without any amplification circuit. Since a stray pickup and electromagnetic interference is typical to the environment of HPM sources, the last feature of the RS is very useful performing measurements at such conditions. Unfortunately, the most successful concept of the waveguide RS with a diaphragm [3] could not be directly downscaled to the millimetre wave range due to small dimensions of the waveguide. A new concept of the RS that is suitable for the millimetre wave region (W-band, 78-118 GHz, waveguide window 2.4 × 1.2 mm 2 ) was proposed in our previous publication [4]. A three-dimensional finite difference time domain (FDTD) calculations have been performed to determine electrophysical parameters of the sensor providing nearly constant sensitivity of the RS in the waveguide’s frequency range. In this contribution, a practical realization of the ideas proposed in [4] is presented. Two groups of the RS made form different specific resistance n-Si were manufactured and tested. A
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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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04405200 - Proceedings of the 37th European Microwave...

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