Integral equation mei applied to three-dimensional arbitrary surfaces

The authors present a new formulation of the integral equation of the measured equation of invariance (MEI) as a confined field integral equation discretised by the method of moments, in which the use of numerically derived testing functions results in an approximately sparse linear system with storage memory requirements and a CPU time for computing the matrix coefficients proportional to the number of unknowns.Peer ReviewedPostprint (published version

An old tool and a new challenge for depicting antenna array radiation patterns

This paper is intended for teachers and students dealing with antenna engineering. Graphical tools have historically been used for illustrating many basic features of radiation patterns, such as the position and number of secondary lobes, null angles, and beam steering. This paper describes one of these graphical devices, which has been successfully used by the author as a classroom demonstration in many undergraduate antenna courses. In addition, this traditional demonstration is also discussed in the context of modern computer software, such as MATLAB

An alternate point-wise scheme for Electric Field Integral Equations

A point-wise approach that can be used efficiently in the numerical solution of Electric Field Integral Equations is introduced. The algorithm is based on the so-called magic distance concept, which defines exactly the point-to-point equivalent of a four-dimensional integral. Magic distance values are rigorously obtained in the electrostatic case and their usefulness is demonstrated. The concept is generalized to the electrodynamic case, resulting in a family of very simple magic-distance inspired algorithms that maintain the overall accuracy of Galerkin formulations without appreciable deterioration in the overall accuracy. (c) 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013

On the direct evaluation of surface integral equation impedance matrix elements involving point singularities

The direct evaluation method tailored to the 4-D singular integrals over vertex adjacent triangles, arising in the first-kind and second-kind Fredholm surface integral equation formulations, is presented. A combination of singularity cancellation, reordering of the integrations, and one analytical integration results in 3-D integrals of sufficiently smooth functions, allowing a straightforward computation by standard Gaussian rules. Numerical results demonstrate that the uncertainty about the accuracy of the impedance matrix elements associated to the interaction of vertex adjacent triangles is safely removed

Lens-based Ka-band antenna system using planar feed

This paper presents a simple, low-cost and compact mobile ground terminal antenna for Ka-band satellite communications that operates in the downlink band (19.7-20.2 GHz). The antenna is composed of a shaped dielectric lens which tilts in front of a planar feed to direct the beam. The planar feed is a circularly polarized patch antenna placed inside a cavity. The lens allows a mechanical beam steering from 0° to 57° in relation to zenith with a scan loss of 4.5 dB. In order to show the potential of a planar antenna as a feeder for this application, the proposed system is compared with a previous solution composed of the same dielectric lens and a horn antenna as feeder.info:eu-repo/semantics/publishedVersio

Efficient algorithms for computing Sommerfeld integral tails

Sommerfeld-integrals (SIs) are ubiquitous in the analysis of problems involving antennas and scatterers embedded in planar multilayered media. It is well known that the oscillating and slowly decaying nature of their integrands makes the numerical evaluation of the SI real-axis tail segment a very time consuming and computationally expensive task. Therefore, SI tails have to be specially treated. In this paper we compare two recently developed techniques for their efficient numerical evaluation. First, a partition-extrapolation method, in which the integration-then-summation procedure is combined with a new version of the weighted averages (WA) extrapolation technique, is summarized. The previous variants of WA technique are also discussed. Then, a review of double-exponential (DE) quadrature formulas for direct integration of the SI tails is presented. The efficient way of implementing the algorithms, their pros and cons, as well as comparisons of their performance are discussed in detail