Development of an electronically tunable ultra-wideband radar imaging sensor and its components

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Title: Development of an electronically tunable ultra-wideband radar imaging sensor and its components
Author: Han, Jeongwoo
Abstract: Novel microwave transmitter and receiver circuits have been developed for implementing UWB (Ultra -Wideband ) impulse radar imaging sensor operating in frequency band 0 .2 to 4 GHz . with tunable operating frequency band . The fundamental system design parameters such as the required transmitting pulse power and the pulse duration were estimated for a presumed specific application , the pavement assessment . The designed transmitter is the tunable monocycle pulse generator with tuning capability for the output pulse duration from 450 - to 1200 - ps , and has relatively high transmitting pulse power from 200 to 400 mW . Tuning of the pulse duration was implemented by novel PIN diode switch configuration and decoupling circuit , and boosting of transmitting pulse power was made possible by using a high power pulse driving circuit and SRD coupling circuit . The synchronous sampling receiver system was designed by using the integrated sampling mixer and two reference clock oscillators placed in the transmitter and receiver respectively for timing control . A novel integrated CSH (Coupled -Slotline Hybrid )sampling mixer has been developed along with the design of the strobe pulse generator appropriate for the impulse radar system . The integrated sampling mixer has unprecedented conversion loss of 2 .5 dB for the pulse signal , bandwidth 5 .5 GHz , and dynamic range 50 dB . The introduced UWB LNA (Low Noise Amplifier ) design operating up to 4 GHz should be useful for weak signal detection applications . The design of the UWB microstrip quasi -horn antenna was optimized for short pulse transmission with respect to the input return loss and the pulse stretching effect . For signal detection in the signal processing stage , the background subtraction technique and B -scan data format were used . A novel signal monitoring technique was introduced in the signal processing to compensate the frequency modulation effect of the reference clock . The test results for the complete system with respect to some sample multi -layer structures shows good receiving pulse waveform with low distortion , enough pulse penetration depth for 13 ? ? pavement sample structure , and minimum 1 -in of range resolution .
URI: http : / /hdl .handle .net /1969 .1 /3904
Date: 2006-08-16

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Development of an electronically tunable ultra-wideband radar imaging sensor and its components. Available electronically from http : / /hdl .handle .net /1969 .1 /3904 .

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