In this paper, we propose a novel modified T-shaped planar monopole antenna in that two asymmetric horizontal strips are used as additional resonators to produce the lower and upper resonant modes. As a result, a dual-band antenna for covering 2.4-and 5-GHz wireless local area network (WLAN) bands is implemented. In order to expand the lower band, a multiband antenna for covering the digital communications systems, personal communications systems, Universal Mobile Telecommunications Systems, and 2.4/5-GHz WLAN bands is also developed. Prototypes of the multiband antenna have been successfully implemented. Good omnidirectional radiation in the desired frequency bands has been achieved. The proposed multiband antenna with relatively low profile is very suitable for multiband mobile communication systems.

A novel compact and wideband coplanar waveguide (CPW)-fed sleeve-shaped monopole antenna is proposed. The uniplanar monopole antenna consists of a CPW-fed monopole and two equal ground planes, including rectangular stubs, according to the concept of the sleeve monopole antenna. The proposed antenna has a measured operating-frequency range from 2.05 to 5.14 GHz for a return loss of less than -10 dB. Good radiation characteristics of monopolelike patterns are obtained.

In this article, a novel particle swarm optimization method based on IE3D is used to design a low-profile modified U-slot microstrip antenna. The antenna is printed on a substrate thickness of 0.008λ. Details of the particle swarm optimization method based on IE3D are presented. Experimental results including return loss and far field patterns of the antenna are given. The obtained antenna bandwidth (S11=-10 dB) can be as large as 1.85 times that of a corresponding unslotted rectangular microstrip antenna at 2.4 GHz.

e new version of the Price’s algorithm given in Brachetti et al. [J. Global Optim. 10, 165–184 (1997)]. Its distinguishing features include: (1) The number-theoretic method is applied to generate the initial population so that the points in the initial population are uniformly scattered, and therefore the algorithm could explore uniformly the region of interest at the initial iteration; (2) The simplified quadratic approximation with the three best points is employed to improve the local search ability and the accuracy of the minimum function value, and to reduce greatly the computational overhead of the algorithm. Two sets of experiments are carried out to illustrate the efficiency of the number-theoretic method and the simplified quadratic model separately. The proposed algorithm has also been compared with the original one by solving a wide set of benchmark problems. Numerical results show that the proposed algorithm requires a smaller number of function evaluations and, in many cases, yields a smaller or more accurate minimum function value. The algorithm can also be used to deal with the medium size optimization problems.

The particle swarm optimization algorithm presents a new way for finding an optimal solution of complex optimization problems, where each particle represents a solution to the problem. In this paper a modified particle swarm optimization algorithm is applied to the optimization of the antenna array. Adding an item of integral control and the contractive factor in the modified algorithm can improve its global search ability. Simulation results show that the optimal pattern of the antenna array is able to approach the desired pattern. The results also demonstrate that the modified algorithm is superior to the original algorithm and the nonlinear least-square method.