A hybrid optimization technique is used to synthesize frequency selective surface (FSS) structures composed of periodic arrays of integrated rings and dipole patch elements, printed on dielectric substrates, for microwave filtering applications. The optimization technique is based on the combination of genetic algorithms and neural networks. This hybrid optimization technique is used to determine specific values for the resonant frequency and bandwidth from variations of the FSS structural parameters, such as patch element and periodic array dimensions. The synthesized FSS structure is also analyzed using a fast and accurate wave concept iterative procedure for comparison purpose. Thereafter, prototypes are built and measured. A good agreement is observed between simulated and measured results. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:329–333, 2014

This article presents a bandwidth optimization study of two coupled frequency selective surfaces (FSS).The optimization is performed in two steps. In the first step, a genetic algorithm is developed to synthesize two single FSS crossed dipoles with resonant frequencies equal to 9.5 and 10.5 GHz, to be used in a broadside coupled geometry, separated by an air gap. In the second step, a particle swarm optimization algorithm is developed to determine the optimal value for the air gap length to optimize the geometry bandwidth. Prototypes are fabricated and measured to validate the optimization study results for the two coupled FSS structure. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:711–715, 2013; View this article online at wileyonlinelibrary.com. DOI: 10.1002/mop.27451

In this work, a new ultra wide band circular ring patch antenna is proposed for spectral sensing application as well as the transmission and reception of radiofrequency in cognitive radio systems. The proposed structure has simple design and easy construction, making it reconfigurable by enabling or disabling the parasitic elements coplanar to the antenna. Simulation and measurements results confirm good agreement and adequate antenna response in the frequency range from 3.1 GHz to 10.6 GHz, in terms of the reflection coefficient and radiation pattern, validating the applicability of the proposed structure for cognitive radio systems front-end.Index Terms-Circular ring antenna, cognitive radio, patch antenna, reconfigurable antenna, wideband antenna, UWB.I.

This article presents the optimization process of a microstrip antenna designed to operate with ultra‐wideband applications. This optimization process was accomplished by applying a self organizing multiobjective genetic algorithm (GA) to optimize a geometry aspect of a ring monopole antenna (a slit in the ground plane) considering three objectives simultaneously (bandwidth, return loss and central frequency deviation). Each of these objectives are modeled as dependent of two variables (the slit dimensions) and used in a single weighted compound aggregate objective function in which weights are defined by an adjuster GA that uses another GA to evaluate each combination of possible weights. The results were compared with the ones obtained to the same antenna using a simulator program (Ansoft HFSS) and with the results of a real prototype antenna built from the slit dimension optimal values obtained after the optimization process. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1824–1828, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26945

The synthesis of a simple electronically reconfigurable annular ring monopole antenna using a designing optimisation process based on particle swarm optimisation (PSO) and artificial bee colony (ABC) algorithms is proposed. Several antenna dimensions are selected as objective functions of PSO and ABC and their best solutions are considered as the optimised dimensions of the antenna geometry. Two radio‐frequency p–i–n diodes, connecting the antenna feeding line to two microstrip stubs are used to change the antenna frequency response from ultra‐wideband (UWB), from 3.1 to 10.6 GHz, to narrowband (NB) operation about 5.8 GHz. The antenna design and simulation are performed using Ansoft high‐frequency structure simulator software. PSO and ABC algorithms are written in Java language. Thereafter, antenna prototypes are fabricated and measured for validation purposes. Simulation and measurement results are obtained showing good agreement. The measured optimised impedance bandwidths of the UWB and NB bands are up to 128 and 23%, respectively. Additionally, simulated and measured radiation patterns are very similar when the reconfigurable antenna is operating in OFF‐state (UWB sensing antenna) and in ON‐state (NB transmitting antenna) modes, indicating the proposed antenna geometry as a promising candidate for applications such as UWB and cognitive radio.