Hybrid Polarimetric GPR Calibration and Elongated Object Orientation Estimation

Hai Liu, Xiaoyun Huang, Feng Han, Jie Cui, Billie F. Spencer, Xiongyao Xie

Research output: Contribution to journalArticlepeer-review


Ground penetrating radar (GPR) has been widely applied to the detection of subsurface elongated targets, such as underground pipes, concrete rebars, and subsurface fractures. The orientation angle of a subsurface elongated target can hardly be delineated by a commercial single-polarization GPR system. In this paper, a hybrid dual-polarimetric GPR system, which consists of a circularly polarized transmitting antenna and two linearly polarized receiving antenna, is employed to detect buried elongated objects. A polarimetric calibration experiment using a gridded trihedral is carried out to correct the imbalances and cross talk between the two receiving channels. A full-polarimetric scattering matrix is extracted from the double-channel GPR signals reflected from a buried elongated object. An improved Alford rotation method is proposed to estimate the orientation angle of the elongated object from the extracted scattering matrix, and its accuracy is validated by a numerical test. A laboratory experiment was further conducted to detect five metal rebar buried in dry sand at different orientation angle relative to the GPR scan direction. The maximum relative error of the estimated angles of the buried rebars in the migrated GPR images is less than 5%. It is concluded that radar polarimetry can provide not only richer information than single-polarization GPR, but also a reliable approach for orientation estimation of a subsurface elongated object.

Original languageEnglish (US)
Article number8718348
Pages (from-to)2080-2087
Number of pages8
JournalIEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Issue number7
StatePublished - Jul 2019
Externally publishedYes


  • Azimuth estimation
  • ground penetrating radar (GPR)
  • hybrid polarization
  • subsurface elongated target

ASJC Scopus subject areas

  • Computers in Earth Sciences
  • Atmospheric Science


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