Huang Jiying

The scale-transformation of electromagnetic theory and its applications

The scale-transformation of electromagnetic theory is investigated in detail based on the form of Maxwell equations in scale-transformation being unchanged in different coordinate systems. The relations of electromagnetic parameters in a rectangular coordinate system and in a spherical coordinate system are presented respectively. The scale-transformation invariants for electromagnetic field are derived and their physical meaning is also presented. It is indicated by simulation that the electromagnetic waves located in medium can be considered to be isotropic due to the fact that the size of propagating vector affected by the scale factors and observing azimuth is on a size of 10−9, which provides a new approach for investigating the electromagnetic characteristics of ellipsoidal targets.

The scattering fields for a spherical target irradiated by a plane electromagnetic wave in an arbitrary direction

The relation between corresponding trigonometric functions in two rotating coordinate systems is presented. The transformation formula for a vector in the two rotating spherical coordinate systems is obtained. The scattering fields for a spherical target irradiated by a plane electromagnetic wave in an arbitrary direction are derived. These fields in a particular case retrogress to those available in the literature. The obtained results have great potential in practical applications.

Millimeter wave propagation through a chiral medium model of human trunk

That millimeter wave propagation through a chiral medium of human trunk has been discussed by obtaining the electromagnetic filed, absorbent power, specific absorption rate, temperature field and their distribution in a human trunk model with plane strati calate homogeneous tissues under a normal incidence plane wave. The chiral medium is described electromagnetically by the constitutive relationsD=εE+εβB andB=μH+μβE. The constantsε, μ andβ ate real and have values that are fixed by the size, the shape, and the spatial distribution of the elements that collectively compose the medium. Also, the principle of thermal therapeutics for millimeter wave is discussed preliminaryly.

Rain induced attenuation for 3MM wave band and its measurement system

In this paper, the effect of rain induced attenuation for millimeter wave is discussed. The theory of multiple scattering is used to obtain the solution for the plane wave propagation through a plane parallel medium of thickness L containing randomly distributed nonspherial particles. The coherent field and the total field are studied, respectively. The numerical results are good agreement with experimental data and the multiple scattering effects must be included. A 3mm wave propagation measurement system was made on a 0.8km terrestrial link.

Reflection Characteristics of Layered Media in Polar Mesopause Related to Polar Mesosphere Summer Echoes

Polar mesosphere summer echoes (PMSE) are very strong radar echoes from altitudes close to the polar summer mesopause. The data from sounding rocket campaigns indicate that the radar signal to noise ratio (SNR), electron density and dust charge density of polar mesosphere in summer show obvious layered structure. In this paper the theory of wave propagation in layered media is used to study the reflectance and SNR at each layer in polar mesosphere. The calculated SNR using theory of dusty plasma is found in good agreement with the experimental result, which may imply that the intensity of the radar echoes reflected by the layered structure in polar mesosphere where polar mesosphere summer echoes used to occur can interpret partially the phenomenon of PMSE. In other words, reflection may play an important role in the occurrence of PMSE.

Characteristic of EM-wave anomalous propagation in marine evaporation duct

Based on the atmospheric modified refractivity, the difference between the evaporation duct and the standard atmosphere is analyzed. The propagation path and the transmission loss of the EM waves are calculated respectively by ray-tracing technique and Fourier split-step method of the parabolic equation in standard atmosphere and evaporation duct. The simulation results show that evaporation duct can trap some radio rays to extend the propagation distance of EM wave and result in the appearance of radar blind zone. The characteristic of the EM wave anomalous propagation in marine evaporation duct can help to improve the radar over-the-horizon detection performance.

Study on the Relation Between the Reflectivity and Frequency in Dusty Plasma of the Polar Summer Mesopause

Relation between the volume reflectivity and frequency in view of the polar mesosphere summer echoes (PMSE) is studied using the small-scale structure of electron density caused by charged dust particles. A theoretical expression for the radar volume reflectivity is derived, which agrees with the statistical result. Both the theoretical and statistical results are confirmed with the data obtained from simultaneous observations at three frequencies. Hence the small-scale structure caused by charged dust particles may be a useful tool for the study on the generation mechanism of PMSE.

Electromagnetic complex scattering for a sphere and a conducting plank in K-wave band

The electromagnetic interaction between a target and a conducting plank is investigated utilizing the electromagnetic images method. The complex scattering Held is presented. The scattering cross section in which the electromagnetic interaction has been included is also educed and the simulation is consistent to experiment. Results show that in a definite distance the electromagnetic interaction is least in the medium wave band. In K- wave band, the error induced by the electromagnetic mutual effect between a large scale target and the conducting plank arrive to 20~30%. Comparing with the change versus frequency, the target size affects the complex scattering distinctively, which presents a theoretical reference for electric system design and electromagnetic compatibility.

Distribution characteristic of scattering field for an ellipsoidal target irradiated by an electromagnetic wave from an arbitrary direction

It is of great importance for engineering applications to obtain the expression of scattering field for an ellipsoidal target irradiated by an electromagnetic wave from an arbitrary direction. Literature relevant to this problem is seldom found. In this paper, the scattering field for an ellipsoidal target is presented by utilizing the scale transformation of electromagnetic field and the rotation of coordinate system, with an electromagnetic wave projecting on the target from an arbitrary direction. The obtained result is in good agreement with the solution available from the literature if we consider the scale factors to be unity. Taking a conducting ellipsoidal target for sample, we perform the partial simulations of the ellipsoidal model and a plant leaf model by choosing different scale factors. The obtained results show that the distribution characteristic of scattering field is sensitively affected by the polarization of the incident wave and varies not much with the incident wave angle but changes with the observation point. At some points the scattering energy arrives at its maximum.

The effects of rain clutter on millimeter radar performance

The effects of rain clutter on millimeter radar performance are investigated at 35, 94 and 140GHz frequencies, including rain attenuation, radar reflectivity, maximum radar range and equivalent target cross section.