Source excitation methods for the finite-difference time-domain modeling of circuits and devices

Semouchkina, Elena; Cao, Wenwu; Mittra, R.

doi:10.1002/(sici)1098-2760(19990420)21:2<93::aid-mop5>3.0.co;2-j

Cited by 4 publications

(1 citation statement)

References 8 publications

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“…Despite the popularity of the gap-feed model, these models have an inherent flaw: the drive-point gap introduces errors in the susceptance due to its own susceptance [11]. These errors can be avoided if feed models are implemented that do not physically break the antenna geometry at the drive point.…”

Section: A Backgroundmentioning

confidence: 99%

On the convergence of common FDTD feed models for antennas

Hertel

Smith

2003

IEEE Trans. Antennas Propagat.

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The finite-difference time-domain (FDTD) method is routinely used to calculate the input admittance/impedance of simple antennas. The value of the input admittance/impedance depends on the level of discretization used in the method, and should converge to a final value as the discretization becomes finer. In this paper, the level of discretization necessary for convergence is studied using two common feed models: the hard-source feed and the transmission-line feed. First, the simplest and most naive methods for introducing the voltage and the current in these models are considered, and the results for the admittance are shown not to converge. Next, improved methods for introducing the voltage and current in these models are constructed. The results for the admittance are then shown to converge, and guidelines are offered for the level of discretization needed for convergence. In addition, two general problems associated with the computation of the admittance are discussed: the agreement between admittances computed with different simple feed models, and the agreement between these admittances and measurements.

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Section: A Backgroundmentioning

confidence: 99%

On the convergence of common FDTD feed models for antennas

Hertel

Smith

2003

IEEE Trans. Antennas Propagat.

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Efficient determination of resonance frequencies in resonant structures using the FDTD method

Semouchkina

Cao

Mittra

et al. 2000

Microw. Opt. Technol. Lett.

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In this paper, we present a finite-difference time-domain technique for determining the resonance frequencies of microwa¨e components by deri¨ing the standing-wa¨e patterns rather than simulating the scattering parameter spectra of the component. We show that, compared to the S-parameter spectra simulation technique, the technique proposed herein can sa¨e the time needed to compute the resonant frequencies by an order of magnitude.

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Numerical modeling and experimental investigation of resonance properties of microwave capacitors

Semouchkina

Cao

Mittra

et al. 2001

Micro & Optical Tech Letters

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Investigation of the resonance properties of capacitors is very w x important for microwave applications 1 . As the operation frequency increases, the current flow in the interior of the capacitor is modified in a manner such that inductive effects are induced. In fact, at high frequencies, the capacitors behave like electromagnetic resonators, with undesirable resonances that degrade their performance. With the trend toward increasingly faster integrated circuits, it becomes necessary to search for better geometrical designs for capacitors in these circuits to push the resonant frequencies to higher values. Up to now, resonance processes in capacitors have not been analyzed using the advanced electromagnetic simulation techniques. Typically, capacitor designs are based on experience and approximating formulas that relate the geometry and material properties of a component to its characteristic parameters, such as capacitance, inductance, and resisw x tance 2 . Such design approaches leave much to be desired in terms of accurately predicting the high-frequency characteristics of the capacitors. It is desirable, therefore, to analyze them using the more reliable electromagnetic simulation techniques.The objective of this paper is to study resonance processes in single-layer planar capacitors and capacitor chips by using a powerful and general-purpose field solver, which is based Ž . on the finite-difference time-domain FDTD method. We compute the standing-wave patterns and determine associated resonance frequencies using the FDTD, and validate the results by comparing them with measured S spectra, which 11 confirm that the resonance absorption occurs at the frequencies predicted by the standing-wave simulations. Our simulation approach is useful not only for understanding the resonance processes in capacitors, but also for finding optimum design geometries that provide improved performance at high frequencies. SIMULATION PROCEDUREWe began by simulating the side-fed planar capacitor strucw Ž .x tures see Fig. 1 a described in more detail in Section 3, which were also fabricated and measured experimentally. The excitation for the FDTD simulation was a Gaussian-shaped pulse, with a bandwidth of 15 GHz, which was modulated by a sinusoidal wave of 7.5 GHz. The structures were excited by Ž .Ž . Figure 1 a Geometry of a planar capacitor. b Geometry of a capacitor chip applying the electric-field pulse between the microstrip feed-Ž . line and the ground plane. Perfectly matched layers PMLs were employed at all truncation boundaries of the computational domains, except at the bottom surfaces, which were perfectly conducting ground planes.In addition, we have simulated single-layer capacitor chips w Ž .x Fig. 1 b , with the same dimensions and dielectric material properties as those of the planar capacitors. The simulated capacitor chips comprise two metal plates, with a dielectric layer inserted in between. They are surrounded by air, and have two feedlines attached to the two metal plates from different sides. No ground p...

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Source excitation methods for the finite-difference time-domain modeling of circuits and devices

Cited by 4 publications

References 8 publications

On the convergence of common FDTD feed models for antennas

On the convergence of common FDTD feed models for antennas

Efficient determination of resonance frequencies in resonant structures using the FDTD method

Numerical modeling and experimental investigation of resonance properties of microwave capacitors

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