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.

A novel CPW-fed broadband circularly polarised square slot antenna is proposed and fabricated. The proposed antenna is fed by a CPW with a widened L-type strip along the diagonal line of the square slot. Measured results show that the 3 dB axial-ratio bandwidth of the proposed antenna can reach 17%. The proposed antenna has simple coplanar geometry which can be easily fabricated on inexpensive substrate.

In this paper, a special nonlinear bilevel programming problem (nonlinear BLPP) is transformed into an equivalent single objective nonlinear programming problem. To solve the equivalent problem effectively, we first construct a specific optimization problem with two objectives. By solving the specific problem, we can decrease the leader’s objective value, identify the quality of any feasible solution from infeasible solutions and the quality of two feasible solutions for the equivalent single objective optimization problem, force the infeasible solutions moving toward the feasible region, and improve the feasible solutions gradually. We then propose a new constraint-handling scheme and a specific-design crossover operator. The new constraint-handling scheme can make the individuals satisfy all linear constraints exactly and the nonlinear constraints approximately. The crossover operator can generate high quality potential offspring. Based on the constraint-handling scheme and the crossover operator, we propose a new evolutionary algorithm and prove its global convergence. A distinguishing feature of the algorithm is that it can be used to handle nonlinear BLPPs with nondifferentiable leader’s objective functions. Finally, simulations on 31 benchmark problems, 12 of which have nondifferentiable leader’s objective functions, are made and the results demonstrate the effectiveness of the proposed algorithm.

Adomian’s decomposition method (ADM) is a nonnumerical method which can be adapted for solving nonlinear ordinary differential equations. In this paper, the principle of the decomposition method is described, and its advantages as well as drawbacks are discussed. Then an aftertreatment technique (AT) is proposed, which yields the analytic approximate solution with fast convergence rate and high accurscy through the application of Padé approximation to the series solution derived from ADM. Some concrete examples are also studied to show with numerical results how the AT works efficiently.

A novel small CPW-fed T-shaped antenna for MIMO application is presented. The size of the antenna is only 35% of that of conventional CPW-fed T-shaped antenna, which has satisfied return loss bandwidth and omnidirectional radiation characteristics. A multifeed 8-element planar array is fabricated and measured. It shows that the features of small size, uniplanar structure, good radiation characteristics and small mutual coupling are promising for MIMO applications in compact portable devices.