Electromagnetics in characterizations

Abstract

(cont.) Characterization of the differential guided mode of a coupled-strip transmission line allows us to understand its behaviors in high frequency circuit applications. S-parameters of the differential mode of a coupled-strip transmission line on a multi-layer silicon substrate extracted from 4-port measurements and simulations are de-embedded by the impedance/admittance subtraction method. By accurately determining the input inductance of the connecting pads, the parameters of the transmission line itself can be de-embedded. For the specific substrate profile considered, it is found that there is a practical upper limit on the value of the differential impedance. Baseline estimation for synthetic aperture radar interferometry is used to refine the height estimation of the resulting digital elevation map. Furthermore, preprocessing is used to reduce the effects of local phase inconsistencies caused by noise. By incorporating the information of the ground control points in the height inversion process, the initial estimation of the baseline parameters based on the satellite state vectors and the commonly used high order polynomial fitting can be improved. In this study, a simulated interferogram of a 2-D terrain is generated, and different levels of phase noise as well as uncertainties in baseline parameters are introduced. Five control points are use in a 60 x 60 km area. The platform height is 500 km and the frequency used is in the L-band ...

A unique negative lateral shift is demonstrated in the study of a Gaussian beam either reflected from a grounded slab or transmitted through a slab with both negative permittivity and permeability, which is distinctly different from the shift caused by a regular slab. The incident beam is modeled as a tapered wave with a Gaussian spectrum. The waves inside and outside the slab are solved analytically from Maxwell's equations by matching the boundary conditions at the interfaces. It is shown that the electric and magnetic fields in all regions can be unambiguously determined. Numerical simulations are presented and the amplitudes of the fields as well as the power densities are computed for all regions. A dramatic negative lateral shift of the beam at the exit interface is observed when both e and are negative. Guided waves in an isotropic dielectric slab are analyzed and it is found that modes with real and imaginary transverse wavenumbers can both exist depending on the constitutive parameters of the slab. The guided modes with both real and imaginary transverse wavenumbers inside in a symmetric dielectric slab with negative permittivity and permeability are solved. It is found that for real transverse wavenumbers, there exist cutoffs for all modes. In addition, a guidance condition of the modes with imaginary transverse wavenumbers in the slab is shown to exist, and a graphical method of determining such imaginary transverse wavenumbers of the guided modes is introduced. Propagation of guided waves inside a less dense negative medium is shown to be possible. Time-averaged Poynting vectors in all regions are derived and it is shown that the direction of power flow inside the slab is opposite to the flow outside the slab.