A Full Wave Three Dimensional Analysis of Forest Remote Sensing Using VHF Electromagnetic Wave

Abstract

A forest made of an infinite biperiodic array of trees over a lossy ground, is illuminated by a linearly polarized electromagnetic plane wave in the range of 20 to 90 MHz. Due to the ratio of the wavelength to the array period, only the specular mode is propagative. Therefore, a reflection coefficient is computed and not a backscattering coefficient. It is obtained by means of a full wave approach, based on an integral representation of the electric field. This approach takes into account all possible interactions between each component of the medium as well as ground penetration and provides full information on the phase of the scattered field. Two models of the forest are developed, the two layers one where trees are separated and the four layers one whee the canopy is replaced by an equivalent homogeneous medium. The low frequency (VHF) used here make this homogenization possible and allows one to consider trees with simple shape, the wave being unable to sense details of a tree. 4 Numerical Results 4.1 Validity of the Born Approximation 4.2 Influence of the Age of the Trees 4.3 Influence of the Representation of the Trees 5 Conclusion Appendix A. The Dyadic Green's Function for the 2LM and the 4LM A.1 The Dyadic Green's Function for the 2LM A.2 The Dyadic Green's Function for the 4LM Appendix B. Elements of the Matrix [I kj ] References

A Coherent Model of Forest Propagation— Application to Detection and Localization of Targets Using the DORT Method

“…The total field in the trees is computed using the integral representation of the field given by (1) Where is the total field at the point r in the air layer, is the reference field, is the permittivity contrast between the scatterers (the trees) and the air and is the Green's function of the layered medium [6], [7]. The integral is over the volume containing the trees .…”

Design and Construction of Wideband Vna Ground-Based Radar System With Real and Synthetic Aperture Measurement Capabilities

“…In the past, extensive research on the distribution of sources of the backscattering within vegetation canopies [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] has been carried out and the experiments on agricultural fields have been performed using ground-based radar systems [17][18][19]. Field scatterometers had been utilized at 10 GHz (X-band) [20,21] while other studies [7,[22][23][24][25] had used the 4.75-GHz field scatterometers and the microwave scatterometer C-band (MS-C).…”

Design and Construction of a Near Real-Time Advanced Automated C-Band Scatterometer System

“…Over the past few decades, there has been a considerable number of researchers who investigated the design and development of scatterometer for various monitoring applications [1][2][3][4][5][6][7][8][9][10]. Field scatterometers were employed at 10 GHz (X-band) [1,11], while other studies [12][13][14][15][16][17] used 4.75 GHz field scatterometers and the microwave scatterometer C-band (MS-C).…”