Jiang Yansheng

Experimental studies on GPR velocity estimation and imaging method using migration in frequency-wavenumber domain

Similar to migration in the (k/sub x/, /spl omega/) domain of seismic techniques, this paper presents a approach to focus on ground-penetrating radar (GPR) data and estimate the electromagnetic wave velocity underground. To demonstrate the validity and feasibility of this approach, experimental GPR data are conducted with an object buried in two different kinds medium. It is found that in a homogeneous medium, this approach can be used to estimate the electromagnetic wave velocity underground and improve the imaging resolution.

Compact dual band and circularly polarized microstrip antenna for CNSS

This paper presents a dual band and circularly polarized microstrip antenna for Chinas Compass Navigation Satellite System (CNSS, or “BEIDOU” for its Chinese name). This antenna is single layered, and by embedding two pairs of T-shaped slots close to the edge of the circular patch, this antenna achieves dual band and circularly polarized performance also with a size reduction. The antennas parameters are relatively independent and easy to tune. Measured results fit well with the simulation results we obtained from Ansoft HFSS.

Design of an ultra-wideband dielectric-filled TEM-horn antenna

In this paper a novel dielectric-filled TEM-horn antenna has been designed and the benefit that can be obtained by using dielectric filling into the general TEM-horn is explored. Here we try to do some research on the radiation properties of this proposed antenna with the finite-difference time-domain (FDTD) numerical method, and then give out some conclusions about the improved properties comparing with the general TEM-horn antenna

A design of coaxial-to-horn antenna balun in ultra-wide band applications

In this paper a model from the coaxial to TEM horn antenna is designed and simulated by the method of FDTD (finite-difference time-domain), some important results are given to discuss the advantage of the balun compared with a model with the coaxial connected directly to the horn antenna

The time-frequency interpretation for transient evolution of wave propagation through dispersive medium

The propagation of electromagnetic waves in a linear, dispersive Lorentz medium is calculated using the finite-difference time-domain (FDTD) method; their time-frequency (TF) characteristics are studied using the Gabor extension. Numerical results show that the TF spectrum gives a clear interpretation for transient evolution of ultra wideband pulse propagation through a Lorentz medium.