Surface wave multipath signals in near-field microwave imaging

  • Authors:

  • Paul M. Meaney;Fridon Shubitidze;Margaret W. Fanning;Maciej Kmiec;Neil R. Epstein;Keith D. Paulsen

  • Affiliations:

  • Thayer School of Engineering, Dartmouth College, Hanover, NH;Thayer School of Engineering, Dartmouth College, Hanover, NH;Thayer School of Engineering, Dartmouth College, Hanover, NH;Department of Radiology, Dartmouth Medical School, Hanover, NH;Thayer School of Engineering, Dartmouth College, Hanover, NH;Thayer School of Engineering, Dartmouth College, Hanover and Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, NH

  • Venue:
  • Journal of Biomedical Imaging - Special issue on Microwave Imaging and Emerging Applications
  • Year:
  • 2012

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Abstract

Microwave imaging techniques are prone to signal corruption from unwanted multipath signals. Near-field systems are especially vulnerable because signals can scatter and reflect from structural objects within or on the boundary of the imaging zone. These issues are further exacerbated when surface waves are generated with the potential of propagating along the transmitting and receiving antenna feed lines and other low-loss paths. In this paper, we analyze the contributions ofmulti-path signals arising from surface wave effects. Specifically, experiments were conducted with a near-field microwave imaging array positioned at variable heights from the floor of a coupling fluid tank. Antenna arrays with different feed line lengths in the fluid were also evaluated. The results show that surface waves corrupt the received signals over the longest transmission distances across the measurement array. However, the surface wave effects can be eliminated provided the feed line lengths are sufficiently long independently of the distance of the transmitting/receiving antenna tips from the imaging tank floor. Theoretical predictions confirm the experimental observations.