Long-Range Ultra-Wideband Radar Sensor for Industrial Applications

Ameri, Ahmed Abbas Hussein

kassel university press, ISBN: 978-3-86219-442-1, 2013, 196 Pages

URN: urn:nbn:de:0002-34438

Zugl.: Kassel, Univ., Diss. 2012

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Content: This research work deals with the design of long-range ultra-wideband (UWB) radar sensor for industrial application. The design details include the design of ultra-short, high amplitude pulse generator and ultra-wideband (UWB) antenna. The developed radar sensor was built in a bi-static configuration.
The goal of this work is to cover a maximum detection range of 20m towards targets with lower reflection coefficients such as bricks with a dielectric constant r of about 4.5. To achieve this goal, a novel ultra-short, high power pulse generator (radar pulser) has been developed. The new pulser consists of a transistor discharge circuit with silicon transistor operating in the avalanche mode and a new step recovery diode (SRD) pulse sharpening circuit. The developed pulse generator produces electrical pulses with an amplitude of 34.5V, a rise-time of 112 ps and a pulse width (FWHM) of 155 ps.
In addition to the generation of ultra-short pulses based on silicon avalanche transistor and SRD pulse shaping circuit, the generation of ultra-short high power pulse based on modern GaAs MESFET devices was also investigated in this work. Two-terminal and three-terminal I-V measurements were carried out to study the breakdown phenomenon of this transistor type. By splitting the conventional avalanche pulse generator circuit into separated charging circuit and separated discharging circuit, a new technique to generate ultra-short high-power pulses was found. Through this approach, very fast high amplitude pulses with rise-time of 136 ps, pulse width (FWHM) of 420 ps and amplitude of 169V were obtained.
In order to transmit and receive the generated ultra-short pulses, two different types of TEM horn antenna have been analyzed. First, a horn antenna with cylindrical matching aperture was developed. This antenna exhibits a bandwidth of about 1.45 GHz extending from 250 MHz up to 1.7 GHz. Then, to reduce the size of the TEM horn antenna a novel antenna ‘‘double-ridge horn antenna’’ has been designed. The frequency bandwidth

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