Bragg-scattering resonance in VHF-SAR forestry data

Bragg resonance is observed in VHF-band SAR data from regularly spaced tree rows. Enhanced backscattering is present when the look direction is perpendicular to the rows. Given a constant row spacing, Bragg resonance will occur for higher frequencies as the incidence angle decreases. Analysis of narrow-band data confirm this mechanism. Periodic intensity patterns are also observed in selected stands, which are related to dislocations and/or small changes in row spacing. The resonance frequency can be used to determine row spacing and thinning.