The particle swarm optimization (PSO) method has been successfully applied to different electromagnetic optimization problems. Because of the complexity of this kind of problems, the associated cost function is in general computationally expensive. A fast convergence of the optimization algorithm is hence required to attain results in short time. Here few variations over the standard algorithm, referred to as differentiated meta-PSO, aimed to enhance the global search capability, and to improve the algorithm convergence, are introduced. In order to verify their effectiveness the different techniques have been first applied to benchmark test functions and then used for the optimization of a planar array

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The design of a rectangular dielectric resonator antenna (DRA) operating in the Ku frequency band is addressed in this letter. Since the DRA has to be used as the radiating element of a transmitting array of active integrated antennas, its input impedance must exhibit a proper resistive load at the fundamental resonance frequency, as well as a dominant reactive behavior, either inductive or capacitive, at higher harmonics. Then, the configuration here proposed is a slot-coupled DRA where harmonic tuning is performed by resorting to the introduction of a couple of additional slots parallel to the conventional main coupling slot. The modified DRA is characterized by the same complexity level as the nontunable counterpart. Samples of simulation results are shown to demonstrate the capabilities of the proposed slot-based harmonic tuning technique for rectangular DRAs

An innovative three-step procedure for the synthesis of linear phased arrays with nonuniformly spaced elements is presented. The main objective is to obtain an array with a minimal number of elements and an optimal efficiency of the amplifiers driving the elements. The procedure consists of three steps. First of all, a periodic array with a single-amplitude tapering and as much phase tapering as there are required shaped patterns is derived. Then, starting from the results of the first step, an equiamplitude nonperiodic array, with a number of phase tapering equal to the number of required patterns and with a minimum number of radiators is synthesized. Finally, a numerical optimization permits refining the results so as to satisfy the design constraints.