Full-wave Approach Research Articles

SUSPENDED SUBSTRATE STRIPLINE BANDPASS FILTERS WITH SOURCE-LOAD COUPLING STRUCTURE USING LUMPED AND FULL-WAVE MIXED APPROACH

This paper presents the design of two suspended substrate stripline (SSS) bandpass fllters (BPFs), both with a source-load coupling structure embedded to create a transmission zero (TZ) near each side of the passband edges. For the flrst BPF, the physical circuit layout is proposed flrst and followed by the establishment of an equivalent LC circuit. The optimization of element values of the LC circuit using a circuit-level simulator leads to quick adjustment of the structural parameters of the physical circuit layout with the aid of a full-wave simulator. For the second BPF, the ingenious equivalent LC circuit modifled from that of the flrst one is proposed for bandwidth enhancement, which is achieved by exciting two extra loaded resonances in the passband. With the element values of the LC circuit optimized, proper reshaping the physical circuit layout from that of the flrst BPF is easily accomplished. The presented lumped and full-wave mixed approach is very e-cient in that the circuit- level simulator is used to the largest extent and the time-consuming full-wave simulator is employed only at the later stage of the design. Experiments are conducted to verify the design of the two SSS BPFs and agreements are observed between the measured and simulated data.

Mode Excitation in the Coaxial Probe Coupled Three-Layer Hemispherical Dielectric Resonator Antenna

In this paper, a coax-probe excited multilayer dielectric resonator antenna (DRA) structure is rigorously analyzed from the modal perspective. The full-wave Green's function approach is presented for the analysis of such multilayer structures with an arbitrary number of layers with greatly reduced computational overhead. Additional reduction in computation time is demonstrated for a centered probe. Also, the modes of the multilayer DRA can be identified from the analysis, which can be used to explain the broadband nature of the coupling. The layer permittivities are optimized for broadband operation of the coax-fed DRA. The bandwidth enhancement for a centered and offset probe is seen to be due to a combination of several DRA modes and the probe resonance. Frequency tuning of the antenna structure is also demonstrated by exciting the antenna at a higher order mode, maintaining the broadband characteristics. The radiation characteristics of the antenna are also investigated.

Simulation of complex plasmonic circuits including bends

Using a finite-element, full-wave modeling approach, we present a flexible method of analyzing and simulating dielectric and plasmonic waveguide structures as well as their mode coupling. This method is applied to an integrated plasmonic circuit where a straight dielectric waveguide couples through a straight hybrid long-range plasmon waveguide to a uniformly bent hybrid one. The hybrid waveguide comprises a thin metal core embedded in a two-dimensional dielectric waveguide. The performance of such plasmonic circuits in terms of insertion losses is discussed.

Cascaded Microwave Network Approach for Power and Signal Integrity Analysis of Multilayer Electronic Packages

In this paper, an efficient cascaded microwave network approach is presented for power and signal integrity analysis of multilayer printed-circuit boards (PCBs) and advanced electronic packages with multiple signal traces, multiple power-ground plates, multiple vias, and external loads such as decoupling capacitors. Each parallel-plate pair, which consists of two consecutive conductor plates functioning as either power or ground in the PCBs or packages, is modeled as one individual microwave network. Equivalent circuits are used in the microwave network to model the vias, and a parallel-plate impedance matrix is formulated to account for the wave interactions between the vias and the boundary of the PCB or package. If signal traces are present in a plate pair, a modal decomposition and recombination approach is employed to model two associated modes: the transmission line mode for the signal traces, and the parallel-plate mode for the power-ground plate pair. The microwave networks for each plate pair are finally cascaded together by enforcing the continuity of the voltages and currents at the via clearance holes in the conductor plate shared by two consecutive plate pairs. Numerical validation reveals that the cascaded microwave network approach produces accurate simulation results with much less central processing unit time and memory requirements than 3-D full-wave approaches.

Shielding Effectiveness of Periodic Screens Against Finite High-Impedance Near-Field Sources

The shielding effectiveness of artificial periodic screens is investigated with reference to high-frequency high-impedance near fields produced by arbitrarily oriented electric dipoles. The screens are formed by metallic objects of arbitrary shape displaced in a 2-D lattice. The problem is first studied through a full-wave approach, using the array scanning method in conjunction with a periodic method of moments in the spatial domain. Next, the shielding problem is solved analytically in some characteristic electromagnetic compatibility configurations through the use of approximate low-frequency homogeneous models together with a classical analysis in the spectral domain. Finally, the solutions are compared with those deriving from the use of the so-called transmission-line approximation. The provided results show the suitability of the analytical approaches in dealing with finite sources different from standard plane-wave excitations and give a useful tool for the design of periodic shields.

Structural, electronic, elastic and optical properties of fluoro-perovskite KZnF 3

We determine the structural, electronic, elastic and optical properties of fluoro-perovskite KZnF 3 using the full potential linear augmented plane wave approach (FP-LAPW) based on the density functional theory (DFT). The exchange-correlation potential is treated by the local density approximation (LDA) and the generalized gradient approximation (GGA). The calculated structural parameters are in good agreement with the available data. We have obtained an indirect band gap. The effect of the pressure on the band gaps is investigated. We evaluate the elastic constants ( C ij ), elastic moduli and the Debye temperature. The imaginary and the real parts of the dielectric function ε( ω) and some optical constants are also calculated.

Azimuthal Mode Coupling in Coaxial Waveguides and Cavities With Longitudinally Corrugated Insert

Coaxial resonant cavities with longitudinal corrugations on the inner conductor are used in high-frequency high-power gyrotrons as means to reduce the number of possible competing modes. For a sufficiently large number of corrugations, the analytical approach usually treats the surface corrugation as a homogeneous surface impedance to obtain simple formulas for the characteristic equation and field components. These formulas can be introduced to interaction codes in a quite straightforward way. Full-wave approaches that account for the azimuthal periodicity of the structure and consider azimuthal spatial harmonics to describe the field distributions have been also employed, increasing though the complexity of the solution and the effort given in numerical calculations. In this paper, a full-wave code is used in an attempt to identify the way that the azimuthal spatial terms contribute to the reformation of the eigenvalue spectrum and propose a criterion for the selection of the spatial terms that should be taken into account for accurate enough calculations.

A fast integral equation method for simulating high-field radio frequency coil arrays in magnetic resonance imaging

A fast full-wave numerical approach was developed for simulating high-field multi-channel radio-frequency (RF) receive coil arrays in magnetic resonance imaging. To improve the efficiency, the impedance matrix was compressed by a multilevel adaptive cross approximation method. Furthermore, careful organization of multiple coil simulations was applied so that the impedance matrix associated with biological subjects is constructed and pre-conditioned only once. Numerical examples demonstrate the efficacy of the proposed approach for RF coil simulations.

Whistler eigenmodes of magnetic flux tubes in a magnetoplasma

Guided propagation of whistler waves along cylindrical non-uniformities of a dc magnetic field is studied within the framework of a full-wave approach. Conditions are revealed under which such guiding structures, commonly known as magnetic flux tubes, can support volume and surface eigenmodes in the whistler range. The dispersion properties and field structures of whistler eigenmodes guided by flux tubes with an enhanced magnetic field are calculated and analysed for plasma parameters typical of laboratory experiments. The results obtained are useful in understanding the basic features of whistler wave guidance by magnetic flux tubes and can be applied to interpreting the data of the relevant experiments.

Full-Wave Real-Life 3-D Package Signal Integrity Analysis Using Nonconformal Domain Decomposition Method

Advances in interconnect technologies, such as the increase of the number of metal layers and 3-D stacking technique, have paved the way for higher functionality and superior performance while reducing size, power, and cost in today's integrated circuit and package products. However, whether or not the package preserves signal integrity (SI) has become a crucial concern for system designers. In this study, a systematic full-wave numerical approach, based on a nonconformal finite-element domain decomposition method (DDM), is proposed for 3-D real-life circuit/package simulations. First, an automatic domain partitioning strategy is utilized to divide the entire model into a number of sub-domains. Each sub-domain is then meshed independently and an <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">h</i> -version of adaptive mesh refinement is employed. Next, a nonoverlapping DDM is adopted to efficiently solve the finite-element matrix equation. Afterwards, a model-order reduction technique is exploited to compute the multiport spectral responses. SI effects such as signal delay, coupling, and reflection are simulated on a product-level package benchmark. Finally, numerical results verify the analysis and demonstrate the effectiveness of the proposed method.

ANALYSIS ON SHIELDING PERFORMANCE OF METALLIC RECTANGULAR CASCADED ENCLOSURE WITH APERTURES

A full-wave approach is proposed to evaluate the shielding performance of metallic rectangular double-stage cascaded enclosures with apertures. The analysis has been carried out by means of the mode-matching technique and the mixed potential integral equation solved with the Method of Moments. The efiects of the dimension of enclosures, the orientation of apertures, the polarization direction of the incident wave, the aperture thickness and the high-order modes propagating in enclosures are taken into account. The accuracy of the proposed approach is validated by comparing with other methods and numerical simulation results can derive some conclusions: the shielding performance of cascaded enclosures is better than that of single-stage enclosures, the shielding efiectiveness can be improved with increasing the distance between stages in the range, and the shielding performance of the double-stage enclosure with parallel- pattern apertures in horizontal polarization case is better than that in vertical polarization case.

Graded index photonic hole: Analytical and rigorous full wave solution

We present a rigorous full wave approach to the omnidirectional photonic hole (PH), an optical system inspired by celestial phenomena and characterized by a radially graded refractive index $n(r)\ensuremath{\sim}1/{r}^{\ensuremath{\alpha}/2}$. It is analytically demonstrated that light capture is effective for $\ensuremath{\alpha}\ensuremath{\ge}{\ensuremath{\alpha}}_{c}=2$. Our analyses are corroborated by precise numerical simulations of steady-state and time-evolution behaviors. The simulations indicate that the optical energy entering the PH system can be kept in captivity for a time duration ${t}_{d}$ scaling as ${t}_{d}\ensuremath{\sim}1/({\ensuremath{\alpha}}_{c}\ensuremath{-}\ensuremath{\alpha})$ when $\ensuremath{\alpha}$ approaches ${\ensuremath{\alpha}}_{c}$. A crucial difference in the time evolution of fields is shown between the cases with $\ensuremath{\alpha}$ close to and equal to ${\ensuremath{\alpha}}_{c}$.

Analysis of Simultaneous Switching Noise Coupling in Multilayer Power/Ground Planes With Segmentation Method and Cavity Model

An accurate power bus model is essential for predicting noise coupling in high-speed printed circuit board (PCB) and package designs. With a complex multilayer structure, the power bus is often modeled using numerical simulation methods. However, full-wave approaches are computationally inefficient, or even infeasible for extremely complicated geometries. Fortunately, the segmentation method makes it possible to combine different types of models together, and both simulation accuracy and efficiency can be obtained through this “divide-and-conquer” strategy. After segmentation, one of the fundamental blocks is a parallel plane pair. For this block, analytical expressions for the impedance ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Z</i> ) matrix are available for a rectangular plane pair and some special triangular plane pairs. The combination of the cavity model with the segmentation technique has been known to be an efficient way to analyze irregularly shaped multilayer structures. In this paper, this approach is further extended to the general multilayer structures with overlapping planes. Noise-coupling mechanisms are then studied, and the two main coupling mechanisms, the plane edge coupling and the via coupling, are further characterized. Engineering implications on reducing noise coupling in a practical multilayer PCB are discussed through a series of simulation examples.

Fast and Accurate Multi-Layer PDN Analysis for Power Integrity and EMC

Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Cite Icon Cite Search Site Citation Bruce Archambeault, Ketan Shringarpure, Jun Fan, Sam Connor; Fast and Accurate Multi-Layer PDN Analysis for Power Integrity and EMC. International Symposium on Microelectronics 1 January 2010; 2010 (1): 000566–000571. doi: https://doi.org/10.4071/isom-2010-WP2-Paper1 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu nav search search input Search input auto suggest Search

Analysing radiation from a superstrate loaded cylindrical–rectangular microstrip patch antenna with a spaced substrate, using the electric surface current model

Radiation from a superstrate loaded cylindrical–rectangular microstrip patch antenna with an air gap between the ground and the substrate is analysed using the full-wave approach and the electric surface current model. Results are presented in the form of normalised radiation patterns and directivity patterns for various thicknesses of the air gap, to show the effects of the air gap on the radiation from the antenna. Both axial and azimuthal current elements are considered.

Theoretical investigation of the electronic and optical properties of Zn 2OX (X = S, Se, Te) in chalcopyrite phase by full potential methods

A full potential linear muffin tin orbital (FP-LMTO) and linear augmented plane wave plus local orbital (APW + lo) approach is used to investigate the electronic and optical properties of Zn 2OX (X = S, Se, Te) in the chalcopyrite phase. It is found that these compounds are direct band semiconductors and the value of band gap increases as one move from Te to S. The optical properties of these compounds namely the reflectivity, refractive index, extinction coefficient, absorption coefficient, real part of optical conductivity and electron energy loss are calculated and their spectra are analyzed. In addition, the band structure, density of states and the bowing parameter of the Zn 2OX (X = S, Se, Te) semiconductors are also obtained and given. The trends in physical properties are also discussed and compared with the available results.

Modeling Multiple Vias With Arbitrary Shape of Antipads and Pads in High Speed Interconnect Circuits

This letter successfully extends the full-wave semi-analytical approach, based on Foldy-Lax multiple scattering equations and modal expansions, to solve massively-coupled multiple vias with arbitrary shape of antipads and pads in high speed interconnect circuits. The magnetic frill current at the antipad aperture is calculated using finite difference method. Numerical examples of as many as 16-by-16 via array demonstrate that this approach is able to model the multiple vias problem at about five thousand times faster than Ansoft HFSS and yet is within 5% difference of accuracy up to 20 GHz.

FULL-WAVE MODELING OF MULTIPLE VIAS USING DIFFERENTIAL SIGNALING AND SHARED ANTIPAD IN MULTILAYERED HIGH SPEED VERTICAL INTERCONNECTS

A 3D full-wave approach, based on the Foldy-Lax multiple scattering equations, is successfully extended to model massively- coupled multiple vias using difierential signaling and shared antipad in high speed vertical interconnects. For the flrst time, this method has been used and tested on via-pair with shared antipad in multilayered structure. The magnetic frill current source on the port is calculated by using the flnite difierence method. Banded matrix iterative method is applied to accelerate the flnite difierence calculation. Numerical example of 15 signal via-pairs and 20 ground shielding vias in 6- layer board demonstrates that this approach is able to model the via-pair with shared antipad and to include all the coupling efiects among multiple vias. The electrical performances of difierent signal driving schemes are provided and discussed. The coupling crosstalk on various via-pairs is compared. The improvement of signal integrity is shown by using difierential signaling and shared antipad for via-pair in multilayered structure. The results are compared with HFSS and SIwave in accuracy and CPU. The CPU using Foldy-Lax approach is three orders of magnitude faster than using HFSS, and two orders of magnitude faster than using SIwave. The accuracy of Foldy-Lax is within 2% difierence from HFSS up to 20GHz, and outperforms SIwave in accuracy.

Full-Wave Modal Dispersion Analysis and Broadside Optimization for a Class of Microstrip CRLH Leaky-Wave Antennas

In this paper, a planar microstrip composite right/left-handed leaky-wave antenna is analyzed and designed as an infinite 1-D periodic microstrip leaky-wave antenna. A parametric study, based on a full-wave numerical modal approach that analyzes a unit cell using a periodic layered-medium Green's function, is shown to be an efficient approach to accurately design the structure, completely eliminating open-stopband effects and achieving an almost constant radiation efficiency when the beam is scanned through broadside. Results obtained by the proposed approach are compared with those obtained by means of both an artificial transmission-line analysis and a Bloch-wave analysis, which use the full-wave simulation of a finite-length structure. The balanced condition is interpreted in terms of the behavior of the phase and attenuation constants relevant to the radiating harmonic. Furthermore, it is shown how radiation at broadside is guaranteed by the presence of two radiating elements (one series and one shunt) within the equivalent circuit of the unit cell. The effectiveness of the analysis is demonstrated through the design of a finite-length antenna excited by a source at one end.

FIRST PRINCIPLES STUDY OF THE EFFECT OF ORBITAL-DEPENDENT EXCHANGE-CORRELATION POTENTIAL ON THE ELECTRONIC AND OPTICAL PROPERTIES OF Pb(Zr1-xTix)O3

Ab initio calculations have been performed on the electrical and optical properties of Pb ( Zr 1-x Ti x) O 3 ceramics with x = 0.5, which is a perovskite type compound. The Kohn–Sham equations were solved using the full potential linear Augmented Plane Wave approach (FP-LAPW). We used GGA, LDA + U and GGA + U approximations for the exchange correlation potential. The results show that with a proper choice of U eff = U - J, for any atoms of the compound, the theoretical values of band gap and the refractive index have been improved compared to their experimented values.