Optimization of the PML efficiency in 3-D TLM method

Abstract

A new planar spiral antenna with integrated impedance transformer is presented which needs no external balun and can be fed by a coplanar waveguide. The proposed structure has a return loss of <À10 dB over a broad bandwidth of 0.5-5 GHz that is suitable for cognitive radio applications. The effects of different spiral and transformer parameters are investigated through various simulations. A case of the proposed antenna is fabricated, and measurement results are presented including return loss, gain, and radiation patterns.ABSTRACT: A novel printed microstrip reconfigurable antenna with three switchable frequencies is proposed. The proposed microstrip-fed Figure 6 Current distribution of the proposed antenna at (a) 0.7 GHz and (b) 2 GHz. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com]

Implementation of the stretched co-ordinate-based PML for waveguide structures in TLM

“…Therefore, the reference solution was truncated at t ¼ 1460Dt to exclude reflections from the boundary. The results show that the performance of the SCB PML is slightly better than those obtained with a non-uniform TLM-FDTD mesh [6] and comparable to those obtained with a unified SCN-TLM mesh [9]. The SCB and CFS PMLs implemented in this paper are performed at maximum time step (7), whereas the unified algorithm presented in Reference [9] was simulated at a time step which is slightly lower than the maximum time step for regular space-stepped non-magnetic material.…”

“…In order to investigate the performance of the SCB PML, we consider a reference problem previously considered in References [6,9], an empty WR-28 waveguide, which has a dimension of 7:112 Â 3:556 mm 2 : As shown in Figure 1, the waveguide is discretized into 36Dl in width, 18Dl in height, and 60Dl in length ðDx ¼ Dy ¼ Dz ¼ DlÞ: Twenty-five PML layers are placed at both ends of the waveguide as illustrated in Figure 1. The dominant mode TE 10 is generated using an amplitude-modulated Gaussian pulse (centre frequency: 42:18 GHz; bandwidth: 15 GHz).…”

“…A uniform type of a twodimensional (2-D) TLM mesh, which can simulate usual and PML media at once, was developed [7]. A modified symmetrical condensed node (SCN) which allows direct Contract/grant sponsor: Korea Science and Engineering Foundation implementation of Berenger's PML in a three-dimensional (3-D) TLM method was proposed [8], and the PML efficiency in the 3-D SCN-TLM method was then extensively discussed in terms of the profile of numerical conductivity values [9]. The PML formulated for the SCN-TLM [8] was later extended to attenuate evanescent waves [10].…”

A hybrid Boundary Element Unstructured Transmission-line (BEUT) method for accurate 2D electromagnetic simulation

“…It must be noted that there are methods to obtain good absorbing boundary conditions through the use of a Perfectly matched Layer (PML) in TLM [24]- [26], however these methods are still inferior to PMLs previously implemented in FDTD [27,28]. The use of BEM to truncate the UTLM mesh gives more accurate boundary conditions that can be applied directly to the surface of the scatterers and also allows spatially distinct scatterers to interact without modelling the space between.…”

Simulation of Ultra Wideband Microstrip Antenna Using Epml-TLM

“…Soon after, a uniform type of a 2D-TLM mesh for modeling usual and PML media was introduced. Following this work a new model based on the SCN node was developed by Dubard for implementation of the Berenger's PML in 3D TLM method [6]. Two other types of 3D PML-TLM nodes were developed by authors [7].…”