Abstract-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.
The canonical Particle Swarm Optimization (PSO) algorithm is known to be very good solution for EM optimization problems. In this paper we present results for a few modifications of the PSO algorithm (Fully Informed PSO algorithm and Repeated PSO algorithm) when they are applied to the optimization of a broadside antenna array. The aim is to find out if and under what circumstances these modifications can give better results than the canonical PSO algorithm. According to obtained results, the well set-up canonical PSO algorithm (with appropriately chosen parameters), outperforms its modifications for EM optimization problems. The number of particles in the swarm seems to be proportional to both the number of dimensions of the optimization problem and the number of iterations.
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