Publications

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This report presents analytic transmission line models for calculating the shielding effectiveness of two common calibration standard cables. The two cables have different canonical aperture types, which produce the same low frequency coupling but different responses at resonance. The dominant damping mechanism is produced by the current probe loads at the ends of the cables, which are characterized through adaptor measurements. The model predictions for the cables are compared with experimental measurements and good agreement between the results is demonstrated. This setup constitutes a nice repeatable geometry that nevertheless exhibits some of the challenges involved in modeling non-radio frequency geometries.

This report estimates inductively-coupled energy to a low-impedance load in a loop-to-loop arrangement. Both analytical models and full-wave numerical simulations are used and the resulting fields, coupled powers and energies are compared. The energies are simply estimated from the coupled powers through approximations to the energy theorem. The transmitter loop is taken to be either a circular geometry or a rectangular-loop (stripline-type) geometry that was used in an experimental setup. Simple magnetic field models are constructed and used to estimate the mutual inductance to the receiving loop, which is taken to be circular with one or several turns. Circuit elements are estimated and used to determine the coupled current and power (an equivalent antenna picture is also given). These results are compared to an electromagnetic simulation of the transmitter geometry. Simple approximate relations are also given to estimate coupled energy from the power. The effect of additional loads in the form of attached leads, forming transmission lines, are considered. The results are summarized in a set of susceptibility-type curves. Finally, we also consider drives to the cables themselves and the resulting common-to-differential mode currents in the load.

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A first principles calculation for the transfer capacitance of a Beldon cable is carried out by the use of filamentary constant, dipole, quadrupole, and octopole unknown charges placed at the center of each braid wire. Results are compared with full electrostatic simulations and a phenomenological model. © 2011 IEEE.

Simplified wire-type models for split-ring resonators (SRRs), both in free-space and above a dielectric half-space, are developed. The gap of the SRR in the wire model is accurately represented by including a lumped load which is the difference between the actual gap fringe capacitance and the capacitance inherent in the code wire kernel for a delta gap voltage source. The SRR arms are represented by generalized thin wires that have both an electric equivalent radius (for the rectangular conductor resting on a dielectric substrate) and a magnetic equivalent radius (for a rectangular conductor in free space, since the substrate is assumed to be nonmagnetic). In addition, an impedance per unit length (due to finite penetration of the fields into the metal) enters a local transmission line part of the generalized thin-wire algorithm. The results from the thin-wire subcell model are compared to full wave simulations of the arrays of SRR's. The full wave simulations require tens of thousands of unknowns to resolve the field penetration into the finite conductors for a single SRR, whereas the thin-wire model has good accuracy with only tens of unknowns. © 2011 IEEE.

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This paper presents a mixed-potential integral-equation formulation for analyzing 1-D periodic leaky-wave antennas in layered media. The structures are periodic in one dimension and finite in the other two dimensions. The unit cell consists of an arbitrary-shaped metallic/dielectric structure. The formulation has been implemented in the EIGER™ code in order to obtain the real and complex propagation wavenumbers of the bound and leaky modes of such structures. Validation results presented here include a 1-D periodic planar leaky-wave antenna and a fully 3-D waveguide test case. ©2010 IEEE.

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This paper presents a mixed-potential integral-equation formulation for analyzing 1-D periodic leaky-wave antennas in layered media. The structures are periodic in one dimension and finite in the other two dimensions. The unit cell consists of an arbitrary-shaped metallic/dielectric structure. The formulation has been implemented in the EIGER{trademark} code in order to obtain the real and complex propagation wavenumbers of the bound and leaky modes of such structures. Validation results presented here include a 1-D periodic planar leaky-wave antenna and a fully 3-D waveguide test case.