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In this paper, a novel optimization method based on single objective, that is, minimization of sideband radiation (SBR) of ultra-low side lobe, narrow beam patterns in time modulated antenna arrays (TMAAs) is proposed. The proposed method utilizes the weighting vectors of the low side lobe Dolph-Chebyshev/Taylor series patterns as the dynamic excitation coefficients of the desired pattern at fundamental radiation. Differential evolution algorithm is employed to distribute the static amplitudes and switch-on time durations in such a way that in the optimization process, dynamic excitation distribution remains the same. Static amplitudes are perturbed in a predefined search range of (0.25, 1), whereas the weighted values of switch-on time durations are obtained by dividing dynamic excitation coefficients by static amplitudes. The technique greatly simplifies the difficulties of multi-objective TMAA synthesizing problem by reducing it to a single-objective optimization problem. Numerical examples for a 32-element linear array are presented to produce ultra low side lobe Taylorand Dolph-Chebyshev pattern with low value of maximum sideband radiation (SBRmax). The optimization results of the proposed method are also compared with those obtained by other optimization techniques, which have been reported previously. [ABSTRACT FROM AUTHOR]

In this paper, a method based on the clonal selection algorithm (CLONALG) is presented to design a reconfigurable dual-beam linear antenna array with excitation distributions differing only in phase. The CLONALG is a relatively novel population-based evolutionary algorithm inspired by the clonal selection principle of the human immune system (IS). From the practical implementation viewpoints, the proposed method takes discrete phase shifters into account during synthesis. Numerical examples showing a good agreement between the desired pattern and the synthesized pattern by using CLONALG are given. [ABSTRACT FROM AUTHOR]

A novel approach to arbitrary array pattern synthesis utilizing weighted biorthogonal modes is presented in this paper. The algorithm, involving arrays with arbitrary geometry and incorporating mutual coupling effect, can accurately determine element excitations required to yield desired field pattern. The mutual orthogonality of modes is used to ensure the agreement between the desired and computed patterns. The effectiveness of the method is demonstrated with several numerical examples. [ABSTRACT FROM AUTHOR]

This paper presents a three-dimensional (3-D) localization system for ultra-wideband (UWB) impulsive noise sources. The localization algorithm is in terms of time difference of arrival (TDOA). Firstly, a feasibility study of the 3-D localization scheme is carried out numerically. Then, the effectiveness and limitation of the scheme are revealed. Our proposal is validated by measurement in an open site. [ABSTRACT FROM AUTHOR]

In this paper new stability theorems for Yee's Finite Difference Time-Domain (FDTD) formulation are derived based on the energy method. A numerical energy expression is proposed. This numerical energy is dependent on the FDTD model's E and H field components. It is shown that if the numerical energy is bounded, then all the field components will also be bounded as the simulation proceeds. The theorems in this paper are inspired by similar results in nonlinear dynamical system. The new theorems are used to prove the stability of a FDTD model containing non-homogeneous dielectrics, perfect electric conductor (PEC) boundary, nonlinear dielectric and also linear/nonlinear lumped elements. The theorems are intended to complement the well-known Courant-Friedrich-Lewy (CFL) Criterion. Finally it is shown how the theorems can be used as a test, to determine if the formulation of new lumped element in FDTD is proper or not. A proper formulation will preserve the dynamical stability of the FDTD model. The finding reported in this paper will have implications in the manner stability analysis of FDTD algorithm is carried out in the future. [ABSTRACT FROM AUTHOR]