Improving the resolution of a stepped frequency cw ground-penetrating radar

Alan Langman; Michael R. Inggs; Benjamin C. Flores

doi:10.1117/12.186729

14 September 1994 Improving the resolution of a stepped frequency cw ground-penetrating radar

Alan Langman, Michael R. Inggs, Benjamin C. Flores

Proceedings Volume 2275, Advanced Microwave and Millimeter-Wave Detectors; (1994) https://doi.org/10.1117/12.186729
Event: SPIE's 1994 International Symposium on Optics, Imaging, and Instrumentation, 1994, San Diego, CA, United States

Abstract

One of the major problems in sub-surface radar is the compromise between resolution and penetration depth. Stepped frequency continuous wave radars (SFCW) have improved the penetration depth of sub-surface radars by achieving greater sensitivity, instantaneous dynamic range, and better spectral control than conventional pulsed systems. However, the resolution in SFCW radar systems is limited by the fast Fourier transform (FFT) processing required to extract depth (i.e., range) information from the vector frequency data. This paper investigates the potential use of the extended prony method for range extraction in a SFCW ground penetrating radar (GPR). This method fits data to a complex exponential model, without placing the restriction on the data that the targets are constrained to definite range bins. This allows for the resolution of the system to go beyond the limitations set by the bandwidth of the waveform. Simulations are presented to examine the effects of the signal-to-noise ratio (SNR) on performance, when applying the extended prony method to a simple GPR model. At all times the results are compared with the standard FFT processing. A prototype radar system has been constructed at the University of Cape Town using standard laboratory equipment, a computer and additional digital and rf circuitry. The antennas used are two ridged wideband horns. Targets were buried in a sandpit and measurements were taken over a 2 GHz bandwidth with a center frequency of 3 GHz. Comparisons ware made between the FFT and the extended prony method for different portions of the system bandwidth, showing the extended prony method can achieve high resolution using a reduced bandwidth.

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Alan Langman, Michael R. Inggs, and Benjamin C. Flores "Improving the resolution of a stepped frequency cw ground-penetrating radar", Proc. SPIE 2275, Advanced Microwave and Millimeter-Wave Detectors, (14 September 1994); https://doi.org/10.1117/12.186729

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