A technique for the synthesis of antenna arrays that can account simultaneously for Near-Field Focusing on one or more spots and Far-Field specifications is proposed, to deal with Wireless Power Transfer applications. The technique is based on the minimization of a properly defined cost function accounting for both Near-and Far-Field requirements at the same time, and including a trade-off parameter to balance each specification in the final result. By synthesizing the weights that have to be applied to the elements of the array fulfilling all the specifications, a wireless link between the antenna array and different devices may be established more efficiently, since power radiated at undesired positions or directions can be reduced. Some illustrative examples are presented to show the ability of the method to solve problems with independent specifications for Near-and Far-Field distributions. A prototype of a 16×16 planar array operating at 16 GHz has been realized and characterized; it is shown that it is able to focus on two Near-Field spots and at an assigned Far-Field direction, simultaneously.

An optimisation framework for near field multifocusing on antenna arrays is proposed. Its aim is to obtain the feeding weights that must be applied to the elements of the array so that the antenna focuses on two or more targets simultaneously. The method is based on the definition of a proper cost function, which is minimised using an optimisation algorithm over an equivalent least squares problem. The success of the technique is noted in the fact that different array parameters can be obtained: magnitude and phase of the array elements or only phase synthesis. In order to show the efficiency of the method, several tests are carried out using different arrays and optimisation parameters. The simulation, manufacture and measurement of an 8 × 8 planar array able to focus on two different targets is also performed. Results show how the framework can be applied to general arrays and demanding requirements, so it may be easily extended to different synthesis problems besides multifocusing.

Traditional synthesis methods usually deal with the Array Factor information or with approaches based on considering ideal radiating elements without interaction between them. Taking into account the coupling between elements increases the complexity of the synthesis tasks, so it is usually disregarded assuming a certain error in the solution. As shown in the paper, this error can be unacceptable in some antenna array designs. A neural network-based solution can exploit the "a priori" knowledge of the radiating system to relate a given radiated field distribution with the voltages that must be applied to each radiating element taking into account mutual coupling effects without increase of complexity from the designer's point of view. A set of techniques based on the use of neural networks for synthesis purposes are presented in this paper. Results of a prototype of antenna array with feeding values designed using the proposed techniques are also presented

A novel near-field focusing approach based on the use of artificial neural networks (NNs) is proposed. It is able to provide the set of weights or feeding values that must be applied to the elements of an array so that the global radiation/reception pattern is focused on one or more predefined positions in the near environment. Due to the use of a properly trained NN, it is able to work fast enough for real-time applications, such as wireless energy and information transfer where moving devices may require quick adaptation of the radiated field distribution and, hence, of the weights applied to the array. Moreover, the training procedure using examples generated with a convenient electromagnetic analysis tool allows taking into account both the radiation pattern of the elements of the array and the coupling effects between them.

Neural networks and genetic algorithms are combined in a new hybrid technique able to perform synthesis tasks over passive-element antenna arrays, whose radiation pattern is defined by the coupling...

A novel neural-network (NN)-based technique for antenna array synthesis and a prototype of antenna array designed using it are presented. This technique is able to calculate the voltages that must be applied to the radiating elements considering all the physical properties of each element of the array and the coupling effects between all of them.