In this paper, propagation of VLF wave in a layered ground model in spherical coordinate system is treated analytically.
Because of the fact that the electrical parameters are not uniform, the ground is regarded as a stratified homogeneous
dielectric layer. Especially in the far field of the earth-ionosphere waveguide the effects by the anisotropic magnetic field
are considered. Finally, some new numerical results and discussions about the far fields are given.
A backscattering model of average signal power function for laser radar range imagery obtained by a
short pulse laser for a coarse cone is presented in this paper. This model can analyze the laser range
profile and range imaging which relate the average power seen by the receiver with laser pulse, target
shape, optical scattering properties of surface material, incidence angle and other factors. Simulation of
the laser range profile and range imaging of a coarse cone is given. Based on the results of the
simulated model and theoretical analysis, the cone can be identified. The model can be used for
demonstration of 3D laser radar system and can also be used to generate library of model data sets for
automatic target recognition.
There has been intense interest in the use of millimeter wave and terahertz technology for the detection of weapons, explosives and other threats. System based on electromagnetic radiation between 30 GHz and 3 THz have advantages that radiation penetrates many common materials, wavelengths are short enough to give adequate spatial resolution and radiation at these frequencies is safe to use on people. It is also applied to the retrieval of tropospheric parameters with the ground-based radiometer system. Tropospheric temperature, humidity and cloud liquid water are key elements in meteorology. Since the 151 GHz channel strongly depends on cloud liquid water, the retrieval accuracy of atmospheric parameters is improved by the inclusion of a channel at 151 GHz. The new retrieval model which uses 123 GHz, 127 GHz and 168 GHz is proposed. Simulations of retrieval are presented based on the radiosonde dataset of Beijing China and the retrieving errors of different methods are compared.
Propagation of a continue THz wave in random coal aggregates are studied using generalized multisphere Mie theory
and Monte Carlo(MC) simulation. Coal aggregates are obtained by the DLA model. Scattering characteristics of
monomers and aggregates in coal clouds are analyzed by generalized multisphere Mie theory. For a single coal monomer
and a coal aggregate, scattering intensities versus scattering angles are given. The effects of the radii of monomers on the
scattering efficiency factors, extinction efficiency factors and absorption efficiency factors are computed and discussed.
With the MC method, the transmission of a THz wave in a coal clouds layers is simulated.
An experiment measuring system is introduced. Angle-resolved single-band and multispectral bidirectional
reflectance distribution function measurements are operated in ultraviolet band. Hemisphere spectral reflectivity of some
samples is measured. An optimizing modeling method, particle swarm optimization (PSO) is used to model the laser
BRDF data of typical samples. The results are fitted with the models developed above using optimize algorithm to get
the parameters. Spectral BRDF of samples calculated with the model are in good agreement with the measured data. And
these studies about measuring and optimizing modeling of typical roughness target samples in ultraviolet band have
significant meanings in a lot of related fields.