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A cylindrically conformal four-element slot array with enhanced axial radiation is proposed in this letter. To realize the axial radiation, first the element adopts conformal dual U-shaped slots with two low-profile cavities to obtain the tilted radiation. Second, four conformal elements integrated uniformly at the circumference of the metallic cylindrical shell are fed by a 1-to-4 microstrip feed network with a 90° sequential phase difference to obtain the axial radiation. Both simulated and measured results are presented and confirm that the 10-dB impedance bandwidth is larger than 400 MHz, covering the frequency range from 3 to 3.4 GHz, and the maximum axial radiation gain is 5.12 dBic. The proposed conformal array has a low profile with only about $0.03{\lambda _0}$ , which can be mounted on the surface of any carrier conveniently.

Based on a new variational method, an even- and odd-mode analysis of transverse coupling slot between waveguides is presented. The proposed method is capable of dealing with slots of finite wall thickness. It uses multiple incident waves with symmetry to simplify the field distribution in the vicinity of the slot, enabling the adoption of one-expansion-term trial functions with sufficient accuracy, even in the instance of wide slots. Analytical solutions are provided, and the calculated results demonstrate excellent agreement with those of numerical simulation. The computation time with the new formulation is, however, significantly shorter. © 1963-2012 IEEE.

In order to overcome the drawbacks of standard particle swarm optimization (PSO) algorithm, such as prematurity and easily trapping in local optimum, a modified PSO algorithm is proposed, in which special techniques, as global best perturbation and inertia weight jump threshold are adopted. The convergence speed and accuracy of the algorithm are improved. The test by some benchmark problems shows that the proposed algorithm achieves relatively higher performance. Thereafter, the applications of the modified PSO in the radiation pattern synthesis of antenna arrays are presented.

A planar structure backed with a cavity is analyzed by a spectral-domain-eigenfunction method. An appropriate basis function and an appropriate weighting function have been chosen, which greatly simplifies the process of the solution. Finally, the calculated radiation fields of the antenna are compared with the measured results. © 1993 John Wiley & Sons, Inc.

A hybrid optimization algorithm that is used in pattern synthesis of linear arrays is introduced The proposed algorithm combines Schelkunoff's zero placement method and genetic algorithm (GA). The problem of pattern synthesis is transformed into searching proper roots of Schelkunoff's polynomial in complex plane. Some roots are placed in term of nulls of the desired pattern, and GA is used to search other roots. When computing side lobes of the pattern, an accelerated algorithm is used to reduce the burden of computation.