A Microwave Tomography System Using Time-Reversal Imaging for Forestry Applications

Abstract

A healthy urban forest is important to improve both human health and overall environmental quality. There is currently a lack in technology that has the ability to evaluate living trees in their natural environment without invasive destructive sampling. This work presents a cost-effective, real-time microwave tomography system for practical forestry applications. The scattering measurement system is designed using wide band microstrip monopole antennas (1-5 GHz) and coupled to a switching matrix and a controlling software for automated real-time data collection. A time reversal signal processing algorithm is developed for performing imaging, based on the measurements. The imaging system is initially validated by imaging simple cylindrical targets and finally utilized for imaging defects in different tree trunk samples. Preliminary experimental results demonstrate the practicality, novelty and benefits of this approach for forestry imaging applications. INDEX TERMS.

Short-range measurements of dielectric and conductive targets using a 38-GHz active incoherent millimeter-wave imaging array

“…High-resolution millimeter-wave imaging can benefit multiple applications such as medical imaging, 1 security screening, 2,3 and non-destructive testing 4 that require sufficient signal penetration through multiple materials and good spatial resolution. Active incoherent millimeter-wave imaging is a recently introduced technique that combines passive interferometric imaging with incoherent noise signal transmission.…”

Non-Destructive Imaging of Defects Using Non-Cooperative 5G Millimeter-Wave Signals

“…There are many works that have tried to combine sensing and communications in a joint waveform, but it is challenging because communications and sensing waveforms and hardware are significantly different such that improving the performance of one modality can inhibit the performance of the other [ 3 ]. Non-destructive testing waveforms usually exploit amplitude and phase information by sweeping their frequency along a wide synthesized bandwidth [ 4 ], while communications signals are instantaneously broadband in order to maximize channel capacity [ 5 ].…”

“…Millimeter-wave imaging is used in a range of applications, including security screening [ 6 , 7 ], non-destructive evaluation [ 4 , 8 , 9 ], medical imaging [ 10 , 11 ], and remote sensing [ 12 , 13 ]. Signals in the millimeter-wave band of the electromagnetic spectrum with frequencies between 30 and 300 GHz can exhibit fine imaging resolution and very good propagation characteristics through multiple materials including clothing, fog, clouds, and smoke [ 14 , 15 ].…”