Petr Lorenz

TLM-G-a grid-enabled time-domain transmission-line-matrix system for the analysis of complex electromagnetic structures

A Grid-enabled time-domain transmission line matrix (TLM-G) system for full-wave analysis of complex electromagnetic (EM) structures is presented. The emerging Grid technology enables distributed EM simulations in a virtual organization. An introduction to Grid computing is given and a detailed description of the layout of the TLM-G system is made. Furthermore, the measured EM performance, scalability, and accuracy of the TLM-G system are shown.

Network Oriented Modeling of Passive Microwave Structures

Network oriented modeling of the passive microwave circuits provides a useful representation of the circuit and leads to the reduction of the required computer time and memory capacity. The proposed stability criterion allows dividing the simulation or measurement results into two parts representing a lumped elements model and distributed parameters model. The system identification procedure defines the order of the lumped elements model and the positions of poles and zeros in the complex frequency plane. The time-domain simulation results for the input impedance of the bowtie antenna in comparison with a method of moments solution are presented.

A substrate integrated waveguide leaky wave antenna radiating from a slot in the broad wall

This paper presents the application of a substrate integrated waveguide (SIW) for the design of a leaky wave antenna radiating from a slot in the broad wall. The antenna radiates into a beam split into two main lobes and its gain is about 7 dB at 19 GHz. The characteristics and radiation aspects of the antenna are discussed here. The measured antenna characteristics are in good agreement with those predicted by the simulation. Due to the SIW technology, the antenna is suitable for integration into T/X circuits and antenna arrays.

Application of the Stability Criterion to the Passive Electromagnetic Structures Modeling

The full wave time-domain numerical simulation of the 3-D electromagnetic structure yields wide band reaction of the multiport microwave circuit on the input electromagnetic signal. The realization of the system identification procedure demands the preliminary determination of the late-time border and the order of the pole model. The new criterion for their estimation is offered. This criterion is based on the stability of physical poles positions and uses the signature comparison technique as a tool of the distinction estimation. The impulse response reconstruction approach using the late time part of scattered waveform improves accuracy for parameter estimation in comparison with singular value decomposition (SVD) conventional procedure. The verification of the developed model for coplanar resonator is presented

Investigation of Symmetry Influence in Substrate Integrated Waveguide (SIW) Band-Pass Filters using Symmetric Inductive Posts

We present the investigation of symmetry influence in substrate integrated waveguide (SIW) band-pass filters using symmetrical posts for the suppression of TEi0 modes, with i = 2,4, . . .. This is of particular importance for SIW band-pass filters with a wide bandwidth. We show theoretical and experimental results for a particular filter with a bandwidth of more than 28% demonstrating an improvement in the suppression of spurious transmission by 19 dB.

Hybrid Transmission Line Matrix — Multipole Expansion (TLMME) Method

The Transmission Line Matrix (TLM) method, as considered here, is a numerical time-domain technique which has been used since its introduction by Johns and Beurle [1] in 1971 to solve various problems in electromagnetic engineering. In TLM the field is discretized in space and time and modeled by wave pulses propagating and being scattered in a mesh of transmission lines. When radiating electromagnetic structures are modeled the appropriate radiating boundary conditions at the boundary of the computational domain need to be included in the computation. In the literature methods to realize absorbing boundary conditions (ABCs) are discussed [2], [3]. However, these methods give only approximate solutions of the problem.

Discrete and Modal Source Modeling with Connection Networks for the Transmission Line Matrix (TLM) Method

We present a technique for the modeling of discrete and modal sources in the transmission line matrix (TLM) method by means of connection networks. Discrete sources are modeled with connection networks based on parallel and series adaptors of wave digital filters (WDFs). Modal sources are modeled with an ideal transformer network. The scattering matrices of the connection networks are given and their properties are discussed. In a numerical example we show that we could calculate accurately the input impedance of a bowtie antenna using a discrete source with an impulsive excitation. In this way we were able to characterize in the shortest possible time the antenna structure in the whole frequency range. The result of the computation is compared with known measurement results and known simulation results from the literature and shows good accuracy.

High-throughput transmission line matrix (TLM) system in grid environment for the of complex electromagnetic structures

The high-throughput transmission line matrix (HT-TLM) system is a network-based computational system capable of performing high-performance computing (HPC) of complex electromagnetic structures in grid environments. The high portability and modularity of the system enables distributed full-wave time-domain analysis of 3D electromagnetic structures on heterogeneous systems, platforms and networks. Using the distributed approach of the HT-TLM system, the computation of complex electromagnetic problems requiring large amount of memory and large computational time, may be achieved. The advantages and potentialities in terms of computational time for various platforms and heterogeneous combinations of them are shown by computing the input impedance of a wideband bowtie antenna. To validate the results, the computed input impedance is compared with a method of moments (MoM) solution. To demonstrate the future potentialities of numerical analysis in the grid environments, we make a discussion on applying the hybridization techniques for complex problems.

The hybrid transmission line matrix - multipole expansion (TLMME) method for the modeling of electromagnetic structures in unbounded regions

The hybrid Transmission Line Matrix – Multipole Expansion (TLMME) method is focusing on potentially exact modeling of unbounded problems in time-domain electromagnetic computations based on the Transmission Line Matrix (TLM) method. In TLMME modeling the unbounded space is divided into two subregions, the spherical TLM region and the Multipole Expansion (ME) region. The connection between the subregions is found from the continuity condition of the tangetial field components and is modeled by a connection network. In this paper we describe the theoretical background of the TLMME method and give a numerical example of modeling of a patch antenna. Index Terms Time domain analysis, Transmission line matrix methods, Multipole expansion

A grid-enabled time domain transmission line matrix (TLM-G) system for the analysis of complex electromagnetic structures

A Grid-enabled time domain Transmission Line Matrix (TLM-G) system for full-wave analysis of complex electromagnetic structures is presented. The emerging Grid technology enables distributed EM simulation in a Virtual Organization (VO). The Virtual Organization is a dynamic collection of resources, individuals and institutions. The layout of the TLM-G system is presented and its scalability in terms of computational time is shown in several different examples.