Hybrid Full-wave Research Articles

Scalability of Hybrid Full Wave/Asymptotic EM Solver Techniques for Naval Antennas

Analysis of naval antennas is very challenging due to the electrical size of the ship structures and the presence of sea surface. Advances in electromagnetic (EM) simulations have significantly improved the design process for such systems, resulting in reduced testing and costs. In this paper, we will review hybrid computational techniques that are becoming popular to analyze and optimize antenna designs and antenna placement on naval structures. Accuracy of simulations using hybrid full wave and asymptotic techniques will be presented.

Hybrid Full-Wave Analysis of Surface Acoustic Wave Devices for Accuracy and Fast Performance Prediction.

In this paper, a hybrid full-wave analysis of surface acoustic wave (SAW) devices is proposed to achieve accurate and fast simulation. The partial differential equation (PDE) models of the physical system in question and graphics processing unit (GPU)-assisted hierarchical cascading technology (HCT) are used to calculate acoustic-electric characteristics of a SAW filter. The practical solid model of the radio frequency (RF) filter package is constructed in High Frequency Structure Simulator (HFSS) software and the parasitic electromagnetics of the entire package is considered in the design process. The PDE-based models of the two-dimensional finite element method (2D-FEM) are derived in detail and solved by the PDE module embedded in COMSOL Multiphysics. Due to the advantages of PDE-based 2D-FEM, it is universal, efficient and not restricted to handling arbitrary materials and crystal cuts, electrode shapes, and multi-layered substrate. Combining COMSOL Multiphysics with a user-friendly interface, a flexible way of modeling and mesh generation, it can greatly reduce the complicated process of modeling and physical properties definition. Based on a hybrid full-wave analysis, we present an example application of this approach on a TC-SAW ladder filter with 5° YX-cut LiNbO3 substrate. Numerical results and measurements were calculated for comparison, and the accuracy and efficiency of the proposed method were verified.

Fast full-wave technique for CAD of polarizers based on double-ridge waveguide sections

ABSTRACTFull-wave technique for a computer-aided design (CAD) of a wide class of square waveguide 90-degree polarizers based on double-ridge sections is presented. The proposed hybrid full-wave technique for analysis of polarizers is based on the Galerkin method with taking into account the edge condition, mode-matching technique and generalized scattering matrix method. The weighted Gegenbauer polynomials are used as the basis functions taking into account the field asymptotic at the edges when solving the eigenvalue problem for a ridge waveguide. Compact Ku-band waveguide 90-degree polarizers are designed for operation within frequency bands 12–12.5/14–14.5 GHz and 12.1–12.5/17.7–18.1 GHz. VSWR within two operational bands of polarizers is less than 1.04, differential phase shift is about 90° ± 0.5° and 90° ± 1.5°, respectively. The length of polarizers is reduced at a factor about 2 in comparison with the known corrugated square waveguide polarizers.

Scale-Dependent Light Scattering Analysis of Textured Structures on LED Light Extraction Enhancement Using Hybrid Full-Wave Finite-Difference Time-Domain and Ray-Tracing Methods

A multiscale model that enables quantitative understanding and prediction of the size effect on the scattering properties of micro- and nanostructures is crucial for the design of light-emitting diode (LED) surface textures optimized for high light extraction efficiency (LEE). In this paper, a hybrid process for combining full-wave finite-difference time-domain simulation and a ray-tracing technique based on a bidirectional scattering distribution function model is proposed. We apply this method to study the influence of different pattern sizes of a patterned sapphire substrate on GaN-based LED light extraction from the micro-scale to the nano-scale. The results show that near-wavelength–scale patterns with strong diffraction are not expected to enhance the LEE. By contrast, micro-scale patterns with optical diffusion behavior have the highest LEE at a specific aspect ratio, and subwavelength-scale patterns that have antireflection properties show a marked enhancement of the LEE for a wide range of aspect ratios.

Hybrid full‐wave/circuit modelling of spark gaps and its experimental validation

A hybrid full-wave and circuit model for spark gaps was constructed. The spark channel was modelled as a non-linear time-dependent resistor based on Rompe–Weizel's spark formula in SPICE. The linear full-wave model of an air gap and other structures were simulated by the semi-implicit finite-difference time-domain scheme based on the Newmark-beta method. These two models were coupled and simultaneously solved in time domain. The coupled model was tested for different charged voltages and spark lengths, and also validated in comparison with measurements.

Power integrity modeling and measurement of TSV-based 3D IC system with application to the analysis of seven-chip stack

This paper presents power integrity modeling and measurement of through-silicon via (TSV)-based 3D IC system. To leverage the accuracy of a full-wave approach and shorter computational time of a circuit approach, a hybrid full-wave and circuit approach is proposed to model each individual chip consisting of TSVs, on-chip power grids and decoupling capacitors. A cascaded scattering matrix approach is used to model the 3D IC system by combining the results for individual chips, packages and boards. The hybrid modeling approach is demonstrated on a 7-chip stack consisting of 6 via-last and 1 via-middle chips. Modeling results show good correlation with measurement from 0.1 GHz to 20.1 GHz. Power integrity analysis is performed to show the effects of TSVs and vertical natural capacitors (VNCAPs) on the power distribution network in individual chips and the 7-chip stack. The passive VNCAPs in the 7-chip stack are also compared with active capacitors based on measurement. Finally, both modeling and measurement results for a prototype consisting of the 7 stacked chips mounted on a BGA substrate and a PCB are presented. This is probably the first comprehensive power integrity modeling, measurement and analysis of such a complete TSV-based 3D IC system at both chip and board levels.

A hybrid FDTD-SPICE method for the analysis of microwave circuits

A hybrid full-wave electromagnetic (EM) field-circuit simulation method, which aims at accurately analyzing microwave circuits, is proposed. This method adopts the finite-difference time-domain (FDTD) algorithm for the EM simulation, the sophisticated equivalent models in a general circuit simulato r SPICE for the circuit simulation, and hybridizes the FDTD and SPICE by using the equivalent current source (ECS) approach. Moreover, three techniques, which map a lumped circuit into FDTD cells as a wire, surface or volume structure respectively, are thoroughly studied. The formulae of the ECS with these three techniques are derived and introduced in detail, and their influences on the simulation accuracy are analyzed. The proposed method is applied to two sample circuits, a microstrip line and a frequency selective surface (FSS), both of which are loaded with diode pairs. The simulation results are compared with the measurement ones, and good agreement is observed, indicating the accuracy and versatility of the method.

Wavelet-Based Analysis of Lower Hybrid Full-Wave Fields

Wavelet-Based Analysis of Lower Hybrid Full-Wave Fields

Fourier Synthesis of Linear Arrays Based on the Generalized Scattering Matrix and Spherical Modes

This paper presents a novel, simple pattern synthesis procedure for linear equispaced arrays which can be characterized by a generalized scattering matrix (GSM) and whose radiated field can be expressed as a weighted sum of shifted spherical waves. It can be viewed as an extension of the classic design techniques of the Fourier series (FS) method or the Woodward-Lawson frequency sampling method, to the case in which the individual antenna elements' patterns and all interelement couplings are taken into account. The design procedure, which yields the excitations needed to achieve the desired pattern, is based on either the FS or the discrete Fourier transform (DFT) of the spherical mode expansion of the array radiated field, as well as on various properties associated to the FS or DFT coefficients. In this work, to compute the GSM of the array and the spherical mode expansion of the field, a validated hybrid full-wave methodology, based on the finite element method and rotation and translation properties of spherical waves, is used. Numerical results of different synthesized array patterns are presented for different arrays made up of dielectric resonator antennas and cavity-backed microstrip circular patches.

Terminal-to-Terminal Hybrid Full-Wave Simulation of Low-Profile, Electrically-Small, Near-Ground Antennas

An investigation into the simulation and performance of low-profile, electrically-small antennas for unattended ground sensor (UGS) networks is featured in this study. Because UGS transceivers are intended for operation near the ground, ground proximity effects become extremely important for considerations related to antenna efficiency, input matching, radiation pattern, and the overall path loss between the transmitter and receiver nodes. While vertical wire antennas are shown to be less susceptible to path loss, a low-profile alternative is desired for UGS applications and is often required in the fabrication of low-cost, monolithic on-chip, miniaturized systems. In this work, the performances of different transceiver systems utilizing different types of near-ground antenna structures including the dipole, loop, ordinary circular slot, and cavity-backed circular slot are analyzed using a full-wave hybrid approach consisting of the moment method in conjunction with a near-ground asymptotic field propagation model. The figure of merit for comparison among the various configurations is identified as the efficiency factor calculated from the ratio of the input power at the transmitting antenna terminal to the received power at the receiving antenna terminal. The unique features of ground proximity effects as pertaining to near-ground operation are discussed and an optimal radiator is identified from the set of structures analyzed.

Broad-band cavity-backed and capacitively probe-fed microstrip patch arrays

A hybrid full wave method for the analysis of probe-fed infinite phased arrays of single and stacked microstrip patches, backed by metallic cavities, is applied to investigate the combined utilization of the capacitive probe-feeding technique and the cavity enclosure of microstrip patches. The goal is to obtain broad-band microstrip antennas on thick substrates without the limitations due to the generation of surface waves of the conventional microstrip antennas on infinite substrates. A design procedure for the capacitive coupling is investigated and theoretical results for the active input impedance and radiation characteristics of different wide-band antenna designs are presented.