Question

Based on the use of the modified Rayleigh criteria demonstrate mathematically which of these two surfaces will appear bright and dark in an Aircraft C-band radar image with a wavelength (λ) of 7.5 cm and an incident angle (θ) of 48 degree. The first surface is a uniform dry sand field with an average local height (h) of 0.10 cm. The second surface is a uniform cell of dry desert scrub vegetation averaging a local height (h) of 70 cm. Be sure to show the formulas you utilize, all your calculations, and explain your results.

Answer 1

Since, incident angle (θ) = depression angle (γ) as they are verticaly opposite angle.

wavelength (λ) = 7.5 cm

depression angle (γ) = 48⁰

Smooth criteria   

Rayleigh rough criteria

The first surface is a uniform dry sand field with an average local height (h) of 0.10 cm will show smooth criteria as in figure (a) since h is less than 0.40 cm.

The second surface is a uniform cell of dry desert scrub vegetation averaging a local height (h) of 70 cm will show Rayleigh rough criteria as in figure (c) since h is more than 2.29 cm.