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An analytic method is presented to design nonuniformly spaced uniform amplitude antenna arrays (NSUAAs) to have near-Chebyshev radiation pattern. In this method, called zeros matching method (ZMM), the zeros of array factors of NSUAAs are matched with the zeros of the exact-Chebyshev pattern. Some examples are brought to verify the effectiveness of the ZMM approach for both linear and planar NSUAAs.
The aim of this paper is to present the adaptation of an Evolutionary Algorithm, Social Network Optimization (SNO) to multi-objective benchmark function. The algorithm will be presented in his basic implementation and then the modifications will be shown. Then it will be used to find the Pareto front of a sparse array.
In this paper a new evolutionary algorithm, Leadership Based Optimization (LBO) will be presented. It will be tested on some standard benchmark functions to assess his optimization capability. To understand the potentiality of this algorithm, it has been compared with other Evolutionary Algorithms, such as Genetic Algorithm (GA) and Particle Swarm Optimization (PSO). Finally the algorithm will be...
Underwater Communication has a wide range of applications. In the case of a short-range communication system, the use of electromagnetic waves has been recently proposed as an alternative to the mostly used acoustic waves. The design of the antennas to be used for underwater communication is strongly influenced by the electromagnetic properties of the water and therefore, after its design but before...
In this work some results about the design and the analysis of Conformai Reflectarray Antennas (CRAs) mounted on curved surfaces are presented. In particular, a comparison among three different Reflectarray configurations i.e. a planar, a convex cylindrical and a convex spherical RA, all working in the Ka-band, is carried out. In order to highlight the effect of the single or double curvature on the...
In this paper the results of the design and the experimental characterization of a Convex Conformai Reflectarray Antenna are presented. The considered configuration, designed to operate in the Ka band, consists of 43×43 square elements printed on a substrate with a radius of curvature of 20 λ and offset fed. In order to validate the design procedure, a prototype has been manufactured and characterized...
In this paper, we investigate the possibility of using cylindrical antennas for short-range underwater communication in freshwater. The performances of three types of cylindrical antennas are compared: dipole, monopole and folded dipole. In freshwater the wavelength is 9–10 times lower than in free space at a specific frequency. This allows a reduction of the antenna actual length and therefore the...
Recently, the Particle Swarm Optimization (PSO) method has been successfully applied to many different electromagnetic optimization problems. Due to the complex equations, usually calling for a numerical solution, the associated cost function is in general very computationally expensive. A fast convergence of the optimization algorithm is hence of paramount importance to attain results in an acceptable...
In this summary, the feasibility of a wireless communication system to be use by scuba divers in case of danger, adopting radio frequency electromagnetic wave technology, is investigated. Some results on the characterizing feature of the propagation inside the water are reported, together with the principal constrains that the environment introduced on the design of the entire system and of its antenna...
In this paper, some results about the design and the full-wave analysis of Printed Conformal Reflectarray Antennas, able to work in the Ka band, using non-conventional re-radiating elements are presented. They introduce an improvement of the radiation characteristics, and in particular an enhancement of the bandwidth.
This paper presents the results of a study on electrically small wearable antennas, for use in emergency and security applications in the low UHF band, around 860 MHz. Realization of prototypes in textile materials has also been considered and implemented.
The design of a Printed Conformai Reflectarray using non-conventional re-radiating elements is here considered. Results of the full-wave numerical analysis of two different reduced size configurations show that these element produce an improvement of the radiation characteristics, and in particular an enhancement of the bandwidth of the antenna.
In the exploding growth of radio mobile and wireless communication applications, microstrip antennas with its advantages of low cost and flexible fabrications, emerge as the most suitable candidate. The direct antenna synthesis could, however do not result in the optimal antenna configuration, and therefore a possible alternative is considering the problem of optimizing the antenna as a system of...
A reflectarray antenna using flexible dielectric substrate is presented as a potential solution for high-gain THz antenna applications. The element phase compensation is achieved by appropriately tuning the flexible dielectric slab height. An equivalent circuit model is built to calculate the element reflection coefficient. A 30mm × 30mm square aperture dielectric reflectarray is then designed and...
A reflectarray antenna combines the advantages of reflectors and phased-arrays. Due to its low profile, low loss, and versatile radiation properties, it has emerged as a new generation of high-gain antennas. Meanwhile, terahertz (THz) technology, which locates between microwave and infrared, is a frontier of the state-of-the-art electromagnetic research. Recently, the concept of reflectarray has been...
In recent years, evolutionary algorithms have been successfully adopted for the optimization of various electromagnetic problems. One of the most common electromagnetic application is in the framework of microstrip antennas, thanks to the advantage of being low cost and low profile. In order to reduce the computational effort of the electromagnetic optimization, a suitable equivalent model by ANN...
In recent years there has been an increasing attention to novel evolutionary optimization techniques employed to engineering and real-world applications. Among these, the design of antennas and electromagnetic devices is a well-established field of application. This paper presents a new population based algorithm inspired by the recent explosion of social networks and their capability to drive people's...
In literature heuristic algorithms have been successfully applied to a number of electromagnetic problems. There are a number of approaches to build up the associated cost functions, the most common one is to link with full-wave analysis. However, this modelling method always leads to the point of complexity and high computational expense. Artificial Neural Network is one of the most robust biological...
Data exchange in many underwater applications such as oceanographic data collection, scientific ocean sampling, pollution and environmental monitoring, disaster prevention, underwater system maintenance, recreational scuba diving, is an exciting task. Due to the reduced visibility (for optical) or high attenuations (for radio) link, in most of the cases the communication between different locations...
Recently, some variations of the Biogeography Based Optimization, named MmCn-BBO have been introduced. The newly introduced features were aimed to improve the performances of the standard algorithm. In this paper the authors compare the performances of the different developed schemes, by applying them to several test functions and to real-world electromagnetic problems.
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