Ground-Based 3D Radar Imaging of Trees Using a 2D Synthetic Aperture

• Main Authors: Justin F. Penner, David G. Long
• Format: Article
• Language: English
• Published: MDPI AG 2017-01-01
• Series: Electronics
• Subjects: radar; synthetic aperture radar; back projection; SAR tomography; vegetation scattering
• Online Access: http://www.mdpi.com/2079-9292/6/1/11

Motivated by the desire to gain insight into the details of conventional airborne synthetic aperture radar (SAR) imaging of trees, a ground-based SAR system designed for short-range three-dimensional (3D) radar imaging is developed using a two-dimensional (2D) synthetic aperture. The heart of the system is a compact linear frequency modulation-continuous wave (LFM-CW) radar, a custom two-dimensional scan mechanism, and a three-dimensional time-domain backprojection algorithm that generates three-dimensional backscatter images at an over-sampled resolution of 10 cm by 10 cm by 10 cm. The backprojection algorithm is formulated directly in spatial coordinates. A new method for estimating and compensating for signal attenuation within the canopy is used that exploits the backprojection image formation approach. Several three-dimensional C-band backscatter images of different individual trees of multiple species are generated from data collected for trees both in isolation and near buildings. The trees imaged in this study are about 10 m in height. The transformation of the three-dimensional images to airborne SAR images is described and a sample result provided.