336 Agastra et al.Abstract-By properly exciting higher order modes at an aperture it is possible to achieve higher aperture efficiencies. High efficiency antennas are mandatory in many applications, as discrete lenses, since the single element efficiency deeply affects the efficiency of the whole lens. In this contribution a genetic algorithm is applied to the mode matching analysis of square horns to achieve high radiation efficiency over a relatively wide band.

Taguchi's method is a quality design technique whose applications in numerical single-objective optimization have been recently exploited. In this article, a novel multiobjective (MO) algorithm based on Taguchi's technique is illustrated and its performances assessed. Validation is performed through a comparison between the presented algorithm and a MO genetic algorithm (GA) based optimization, first on different sets of test functions and then on a practical antenna array synthesis problem. Results indicate a generally better behavior of the proposed algorithm in terms of convergence and spreading over the Pareto front with respect to the GA benchmark.

In this article, an algorithm able to deal at the same time with wire frame and surface patch models for the method of moments in time domain is presented. After a unified theory combining both models, attention is focused on stability dependence issues on the time basis function chosen and on other algorithm parameters. An accurate analysis of time interpolation functions and of their time filtering properties is provided.

High efficiency, compactness, light weight and low return loss are of high importance in antennas, especially in space applications. In this contribution a modified nondominated sorting genetic algorithm (NSGA-II) is applied to the design of Horn antennas for discrete lens applications to achieve a Pareto-optimal solution. Horn design is aimed not only towards higher possible efficiency but also towards large band and compactness.

Three ground-backed compact strip-and slot-sinuous antennas are analyzed. Proposed configuration allows for a single lobe, polarization-versatile, high efficiency, and ultrawide band antenna not needing a cumbersome lossy back cavity typical of conventional single-lobe sinuous antennas. Simulations show attained performances as well as tuning possibilities.