Remote sensing of vegetation and soil using microwave ellipsometry

Claim 1

A method of determining the water content and thickness d of a layer of vegetation on a soil substrate of known refractive index n m comprising: transmitting a circularly polarized train of microwaves of wave length λ to a layer of vegetation at a predetermined angle of incidence θ, the orthogonal components of the electric field of said microwaves having equal intensities I i p and I i s and in quadrature in the plane of incidence and normal to it; receiving the orthogonal components of the train of microwaves reflected from the layer of vegetation and the soil substrate; detecting the intensities I r p and I r s of the orthogonal components of the electric field of the received reflected train of microwaves; determining the ratio I r p /I r s of the intensities of the detected orthogonal components of the electric field of the received reflected train of microwaves; measuring the phase difference 90° + Δ of the orthogonal components of the electric field of the received reflected train of microwaves; and computing the refractive index n f and the thickness d of the layer of vegetation from the formula: ##EQU5## wherein r f p , r m p , r f s and r m s are the Fresnel coefficients and are functions of θ, λ, d, n f and n m ; and the refractive index of the vegetation n f is given essentially by the water content of the vegetation.

Claim 2

A method of determining the water content and thickness d of a layer of vegetation on a soil substrate of known refractive index n m comprising: transmitting a circularly polarized train of microwaves of wave length λ to a layer of vegetation at a predetermined angle of incidence θ, the orthogonal components of the electric field of said microwaves having equal intensities I i p and I i s and in quadrature in the plane of incidence and normal to it; receiving the orthogonal components of the train of microwaves reflected from the layer of vegetation and the soil substrate; detecting the intensities I r p and I r s of the orthogonal components of the electric field of the received reflected train of microwaves; determining the ratio I r p /I r s of the intensities of the detected orthogonal components of the electric field of the received reflected train of microwaves; measuring the phase difference 90° + Δ of the orthogonal components of the electric field of the received reflected train of microwaves; and computing the refractive index n f and the thickness d of the layer of vegetation from the formula: ##EQU5## wherein r f p , r m p , r f s and r m s are the Fresnel coefficients and are functions of θ, λ, d, n f and n m ; and the refractive index of the vegetation n f is given essentially by the water content of the vegetation.

Claim 3

A method of determining the moisture of a soil substrate comprising: transmitting a circularly polarized train of microwaves of wave length λ to a layer of soil substrates at a predetermined angle of incidence, the orthogonal components of the electric field of said microwaves having equal intensities I i p and I i s and in quadrature in the plane of incidence and normal to it; receiving the orthogonal components of the train of microwaves reflected from the layer of vegetation and the soil substrate; detecting the intensities I r p and I r s of the orthogonal components of the electric field of the received reflected train of microwaves; determining the ratio I r p /I r s of the intensities of the detected orthogonal components of the electric field of the received reflected train of microwaves; measuring the phase difference 90° + Δ of the orthogonal components of the electric field of the received reflected train of microwaves; and computing the refractive index n m of the soil substrate from the formula ##EQU6## wherein r m p and r m s are the Fresnel coefficients for the orthogonal components and are a function of θ, λ, and n m ; and the refractive index of the soil n m is given essentially by the moisture of the soil substrate.

Claim 4

A method of determining the moisture of a soil substrate comprising: transmitting a circularly polarized train of microwaves of wave length λ to a layer of soil substrates at a predetermined angle of incidence, the orthogonal components of the electric field of said microwaves having equal intensities I i p and I i s and in quadrature in the plane of incidence and normal to it; receiving the orthogonal components of the train of microwaves reflected from the layer of vegetation and the soil substrate; detecting the intensities I r p and I r s of the orthogonal components of the electric field of the received reflected train of microwaves; determining the ratio I r p /I r s of the intensities of the detected orthogonal components of the electric field of the received reflected train of microwaves; measuring the phase difference 90° + Δ of the orthogonal components of the electric field of the received reflected train of microwaves; and computing the refractive index n m of the soil substrate from the formula ##EQU6## wherein r m p and r m s are the Fresnel coefficients for the orthogonal components and are a function of θ, λ, and n m ; and the refractive index of the soil n m is given essentially by the moisture of the soil substrate.