Tsuyoshi Matsuoka

Numerical Analysis of Scattered Power from a Layer of Random Medium Containing Many Particles of High Dielectric Constant -- Application to the Detection of a Water Content of Soil --

This paper shows the scattering cross sections of a random medium which is a simple model of moist soil by analyzing a dense medium radiative transfer equation (DMRT). The parameters in the DMRT, the extinction rate and the scattering coefficient, are calculated by a multiple scattering method called our method in this paper. Our method is valid for particles with high dielectric constant like water drops. Characteristics of the scattering cross section are made clear by changing the fractional volume of water and the incident angle, polarization of incident waves. We discuss the possibility of detection of a water content in this approach by using the characteristics of the scattering cross section.

Electromagnetic wave propagation analysis by using the CIP method and quadratic interpolation

In this paper, a new type of the CIP method which is combined with quadratic interpolation has been proposed. The radiated wave from a line source has been analyzed by using the proposed method and the results have been compared with those of FDTD method and other CIP methods. The comparisons have shown that the accuracy of the proposed method was almost the same as that of Type-C CIP method and that the proposed method had better phase characteristic than FDTD method.

Calculation of scattered power from a layer with randomly distributed particles for the application to the detection of water contents in soil

Moist soil is regarded as the mixture of air, soil, bound water and free water; then it may be assumed a dense random medium. A radiative transfer equation in a dense random medium has been derived from a wave equation with quasi-crystalline approximation with coherent potential (QCA-CP) and ladder approximation, L. Tsang et al. (1987). Under these approximations, a random medium is considered as a homogeneous medium with the effective permittivity, and the scattering and extinction coefficients are evaluated by QCA-CP in Rayleigh scattering region. The radiative transfer equation includes more scattering effects than the conventional one (CRTE), but does not include the effect of backscattering enhancement. This paper considers a three layered model, composed of air, moist soil layer and perfect conductor for developing a method for detecting water contents in soil by active remote sensing. The moist soil layer may be regarded as a homogeneous soil layer with densely distributed water particles. For this model, they used a dense medium radiative transfer equation (DMRTE) with the parameters evaluated by their method to calculate the bistatic scattering coefficients of the soil layer and the degree of polarization of scattered waves by changing the polarization of incident plane waves and the fractional volume of particles.

Analysis of radio wave propagation in building models consisting of concrete with conducting frameworks by the CIP method

The electromagnetic wave propagation in 2D building models of concrete with conducting frameworks is numerically analyzed by using the constrained interpolation profile (CIP) method. The numerical results are compared with experimental results obtained by the experimental scale model. The comparison gives good agreement each other and show the effectiveness of CIP method for analyzing the wave propagation.

2D Wave Propagation Characteristics of the CIP Method with Amplitude Error Compensation

This paper considers the characteristics of 2D wave propagation analysis by the CIP (Constrained Interpolation Profile) method with amplitude error compensation. The amplitude compensation method based on the diversion relation of 1D-CIP method is applied to the 2D-CIP calculation scheme with directional splitting technique. It is shown that the compensation is effective for the analysis of EM propagation with the CIP method.

A Satellite Link-Like Bit Error Model Based on the Received Signal Level for Link Simulator's Error Implementation

Both changes in speed and protocols in data transfer via satellite links will be an attraction for various services and will extend the terrestrial network to remote areas without the need for costly and limited terrestrial network. However, high frequency satellite links are subject to climatic impairments, especially rainfall. In varying weather conditions, these links show wide variations of bit errors and could not allow the achievement of reliable communication. In some existing systems, these problems are solved by providing the system an extra power margin. At these frequencies and above, the link margin is about 10-20dB. If this supply power is provided for a long period of time, the considered system will turn to be inefficient. It seems therefore important to conduct some experiments in order to develop new protocol or improve existing one for an efficient and reliable data transfer. The non-permanent access to satellite links for experimental purposes can be supplied by indoor apparatus or computer software that generates test conditions approximating actual or operation conditions. Up to now, some satellite link simulators are being developed [1]. These simulators use an Additive White Gaussian Noise (AWGN) to generate the channel error which is not generally the case for satellite links under climatic effects. The intent of this paper is to present and evaluate an efficient bit error generation algorithm based on the statistical analysis of the received signal level in practice. This algorithm is one of the key points for developing a satellite link simulator suitable for the design of today and future communication links[2].

An analysis of the effective propagation constant for a composite medium containing sparsely and randomly distributed pairs of dielectric or chiral spheres

In this paper, the composite medium containing sparsely and randomly distributed aggregate spheres is considered. The effective propagation constants of the medium for the left- and right-handed polarization is evaluated by solving the multiple scattering equation using EFA. The T-matrix of the aggregate sphere is obtained by the recursive algorithm. Numerical results show that when the aggregate sphere consists of chiral or dielectric spheres whose size are much smaller than the wavelength, the characteristics of the aggregate sphere depend mainly on the properties of a scatterer of the largest size.

Calculation of scattered power from random medium layers by using radiative transfer theory for the estimation of moisture in soil by microwaves

The detection of a water content of soil is one of important subjects in civil and agricultural engineering. Microwave remote sensing seems to be a promising detection technique because the microwave properties of moist soil are sensitive to water content. Passive and active microwave remote sensing approaches have been studied. Moist soil, composed of air, soil particles, bound water and free water, may be considered as a dense random medium from a theoretical point of view. We assume moist soil as three layers of random medium with flat interfaces, and investigate the effects of particle distribution density in the depth direction for developing a method for detecting a water content of soil by active remote sensing. In each layer, many water drops or soil particles coated by bound water are randomly distributed. The dense medium radiative transfer equation (DMRT), with coefficients estimated by our method, is used to calculate the scattering cross sections of the layers. We clarify numerically the characteristics of the scattering cross sections by changing the fractional volume of particles in the random medium layers, each layer thickness and the incident angle and polarization of incident waves. We finally discuss the possibility of water detection in soil on the basis of the characteristics.

A comparative study of the effective propagation constant in a random medium containing coated dielectric particles

Studies of the propagation and scattering of waves in random media containing dielectric particles have previously been made with applications to remote sensing technology and material science. The particles in natural geophysical terrain and in composite materials consist of different constituents. Therefore it is important to have a medium model containing dielectric particles consisting of two layers with different materials. This model may be used to study waves propagating in media such as melting snow, wet snow, soil moisture and composite materials with coated granules. In this paper, we treat the medium model whose coated spherical particles are randomly distributed. The effective propagation constant (K/sub eff/) in a random medium containing coated dielectric particles has been analyzed by conventional methods: EFA (effective field approximation, Foldys approximation), QCA (quasicrystalline approximation) and QCA-CP (QCA with coherent potential). These methods, however, have been indicated to become invalid for particles coated with a material having high dielectric constant; we have thus presented a new method valid for them. This paper compares K/sub eff/ of our method with those of the conventional methods by changing the volume fraction and the structure of particles. As a result, our method is shown to be more powerful for the analysis of K/sub eff/.

Comparison of scattered powers from a layer containing randomly distributed particles, calculated from a few radiative transfer equations

Let us consider the problem of active remote sensing for detecting water content in soil. A theoretical approach for this problem is one of the important subjects in civil and agricultural engineering as well as experimental approaches. Moist soil can be regarded as a mixture of air, soil, bound water and free water. Then it is considered as a dense random medium. A conventional radiative transfer equation (CRT) has been commonly used to analyze the propagation and scattering of wave intensity in a random medium, but it becomes invalid for a dense random medium. Another radiative transfer equation, which is called the dense medium radiative transfer equation (DMRT), has been derived from a wave equation with the quasi-crystalline approximation with coherent potential (QCA-CP) and ladder approximation. Under these approximations, the random medium can be replaced with a homogeneous medium with effective permittivity evaluated by QCA-CP. In this paper, we consider a three layered model, composed of air, moist soil layer and perfect conductor. The moist soil layer is assumed to be a homogeneous soil layer with densely distributed water particles. For this model, we have used a DMRT with effective permittivity evaluated by the method presented by Tateiba to calculate the backscattering cross section of the soil layer when a plane wave is incident on the moist soil layer. The numerical results of our method are compared with ones of QCA-CP.