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 13Â pavement sample structure, and minimum 1-in of range
resolution.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/3904 |
| Date | 16 August 2006 |
| Creators | Han, Jeongwoo |
| Contributors | Nguyen, Cam |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | 3377296 bytes, electronic, application/pdf, born digital |
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