1,721,005 research outputs found
Contactless energy transfer in adverse environment using rectennas
No full textThe application of a wireless energy transfer system to a rotating shaft is analyzed in this paper
Modified Bayesian optimization algorithm for EMC complex system design
No full textThe design of real electrical, electronic or electromagnetic complex systems fulfilling EMC constrains often exploits the performances of population based global optimizers. One of the main drawbacks of the adoption of these optimizers in the design of a real system is the difficulty in the introduction, in the optimized design algorithm, of all the heuristic knowledge already available in the field. In order to overcome this problem Bayesian optimization algorithms, classified as estimation of distribution algorithm, could be very effective, since they are based on the definition of the distribution of promising solutions by using the information extracted from the entire set of currently good solutions. Unfortunately, their straightforward implementations usually lack of exploration, and are easily trapped in local maxima. In order to overcome even this drawback and to develop a Bayesian optimization algorithm with both the required exploitation, of the heuristic knowledge, and the exploration, for avoiding local maxima, for system or subsystem design fulfilling EMC constrains, in this paper a modified BOA is proposed by adding a suitable mutation scheme to the traditional one in order to ensure the effectiveness of the algorithm. The here proposed new algorithm has been tested on some mathematical test functions and on a typical EM design problem, a microwave microstrip filter synthesis, to show its capability
Improved compact genetic algorithm for EM complex system design
No full textNowadays the design of complex real electrical, electronic or electromagnetic systems may effectively exploit the characteristics of population based global optimizers. One of the main drawbacks of the adoption of these optimizers in the design of a real system is the difficulty in the introduction, in the optimized design algorithm, of all the heuristic knowledge already available in the field. In order to overcome this problem compact genetic algorithms, classified as estimation of distribution algorithm, could be very effective, since they apply and manipulate a suitable probability vector to represent the distribution of good solutions. Unfortunately, their straightforward implementations usually lack of exploration, and they are easily trapped in local maxima. In order to overcome even this drawback and to develop a compact genetic algorithm with both the required exploitation, of the heuristic knowledge, and the exploration, for avoiding local maxima, in this paper a modified cGA is proposed by implementing more probability vectors and adding a suitable learning scheme to the traditional one in order to ensure the effectiveness of the algorithm. The here proposed new algorithm has been tested on some mathematical test functions and on a typical EM design problem, a microwave microstrip filter synthesis
Some preliminary results on conformal Reflectarrays
Full text linkIn this paper, the characteristics of Reflectarray Antennas printed on convex curved surfaces are analyzed. In particular, results on the radiation performances of different Reflectarrays designed to be mounted on cylinders with different radii of curvature are presented and discusse
Reflectarray antenna for X-band satellite communication
No full textThe objective of this work is the design of a 32 #x00D7;32 element X-band reflectarray, in which the re-radiated elements have no conventional shape and enough degrees of freedom to compensate both the spatial and frequency phase variation of the re-radiated field. In particular, here we focus on a re-radiating element consisting in two concentric square rings in which two different and quite independent geometric parameters are varied
Improved compact Genetic Algorithm for thinned array design
No full textA new strategy based on compact Genetic Algorithm (cGA) for the synthesis of linear thinned arrays is here proposed. In order to exploit all available knowledge from Almost Different Set (ADS) for thinned array to obtain very low peak sidelobe level (PSL) suitable probability vectors to represent the solutions have been introduced. As a proof of concept, several thinned arrays have been synthesized and the obtained results are here discusse
A compact printed extremely-wideband MIMO antenna with WLAN band rejection
No full textA printed MIMO antenna with extremely wide-band (EWB) for multi-band wireless applications has been proposed and analyzed in this paper. The designed antenna satisfies the voltage standing wave ratio (VSWR) requirement of less than 2.0 in an extremely wide frequency band ranging from 2.7 GHz to 20 GHz. To enhance the isolation coefficient in MIMO antenna, two parallel strips are added between two radiating elements. Consequently, the mutual coupling coefficient is much below -15 dB for all operating frequency band. In addition, since the bandwidth of this antenna covers frequency bands where several applications and/or services may be simultaneously acting in the considered area, it becomes a very important feature the capability of rejecting the interferences occurring between these systems. In this paper, the introduction of suitable slots as an effective method for sub-band notching has been presented, and, as an example, the WLAN band rejection has been considered in detail. By exploiting the optimization possibilities introduced by the slot structure degrees of freedom, it became possible to obtain the desired band rejection. All the here considered structures have been designed choosing for the substrate the popular FR4, with dielectric constant of 4.4, and thickness 1.6 mm
Dual-parameter concentric ring RA elements
No full textReflectarray antennas (RA) are nowadays a quite well established technology, used in several applications. Nevertheless, they still suffer for some limitations, that are partially due to their intrinsic reduced bandwidth, that could be enlarged, but generally with a drastic increase of the structure complexity. Here we propose a new type of re-radiating element, consisting in two concentric square rings in which two geometric parameters are varied. In this way it is possible to better control both the spatial and frequency phase variation of the re-radiated field. Numerical analysis of reduced size RAs has been carried out, and it confirms the promising characteristics of such radiating element
Design of single layer RA with enhanced bandwidth
No full textIn this paper, a new type of re-radiating element for printed reflectarrays (RAs) is presented. It consists in two concentric square rings in which two geometrical parameters are varied in order to enhance the RA bandwidth. The results of the full-wave, numerical analysis of a 16 #x00D7;16 RA confirm the promising characteristics of such radiating element
Linear Sparse Array Synthesis using Modified Bayesian Optimization Algorithm
No full textIn this paper, a new approach for sparse array synthesis is proposed. It is based on the use of a recently introduced improved version of the Bayesian Optimization Algorithm (BOA), named Modified BOA (M-BOA), that has already proved its outperforming capabilities with respect to the standard BOA as well as other well-know optimization approaches. Moreover, in opposite to what is generally done relatively to sparse arrays, here an asymmetric configuration is considered, so that the number of control parameters that could be managed by the optimizer is doubled. The results on several configurations show that the sparse arrays designed with the approach here introduced outperform those synthesized with other techniques. As a proof of concept, the results relative to a 37 element linear sparse array are here presented and discussed
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