In this article, two particular methods for the synthesis of the complex radiation pattern of a linear and a planar array, based on genetic algorithms (GAs), are discussed. First, we present a combination of Schelkunoff's method and GAs for linear arrays with arbitrary radiation patterns; then, we consider the synthesis of planar arrays with rectangular cells. The results show the flexibility of GAs to solve complex problems related to antenna synthesis, subject to many restrictions which are difficult to treat by classical optimization techniques. There is good agreement between the desired and calculated radiation patterns.

Synthesis of antenna arrays using genetic algorithms

In this paper, we describe an electromagnetic genetic algorithm (GA) optimization (EGO) application developed for the cluster supercomputing platform. A representative patch antenna design example for commercial wireless applications is detailed, which illustrates the versatility and applicability of the method. We show that EGO allows us to combine the accuracy of full-wave EM analysis with the robustness of GA optimization and the speed of a parallel computing algorithm. A representative patch antenna design case study is presented. We illustrate the use of EGO to design a dual-band antenna element for wireless communication (1.9 and 2.4 GHz) applications. The resulting antenna exhibits acceptable dual-band operation (i.e., better than -10 dB return loss with 5.3 and 7% operating bandwidths at 1.9 and 2.4 GHz) while maintaining a cross-pol maximum field level at least 11 dB below the co-pol maximum.

A parallel electromagnetic genetic-algorithm optimization (EGO) application for patch antenna design

Bandpass filters based on guided-mode resonance effects in waveguide-grating structures are obtained by use of a genetic algorithm search-and-optimization routine. Calculated examples show that narrow linewidths, high peaks, and low sideband transmittances can be achieved in thin-film diffractive devices with few layers. A filter with a linewidth of 0.2 nm at a central wavelength of 0.55 microm is demonstrated in a two-layer-two-grating structure. At 10.6-microm wavelength, a filter consisting of a single binary grating is obtained that has a linewidth of 12.7 nm and extended, low sideband transmittance. A three-layer device with a surface relief Si grating and two underlying homogeneous layers of SiO(2) and Si yields a high-efficiency filter centered at 1.55 microm with a linewidth of 0.1 nm.

Narrow-linewidth bandpass filters with diffractive thin-film layers.

Si Tight-Binding Parameters from Genetic Algorithm Fitting

Methods of detecting one or more parameters of a medium are disclosed. The methods include providing a waveguide grating device, contacting the waveguide grating with a medium, propagating a signal having at least one signal attribute through the waveguide, and comparing the modified signal attribute to a known signal attribute to detect a parameter of the medium.

Methods for using resonant waveguide-grating filters and sensors

The feasibility of novel all-dielectric waveguide grating filters is demonstrated, using a genetic algorithm (GA) to solve for material dielectric constants and geometric boundaries separating homogeneous regions of the periodic cell. In particular, the GAs show that simple geometries (not previously reported) utilizing a small number of layers and/or gratings can be found to yield bandpass or stop-band filters with user defined linewidth. The evaluation of the fitness of a candidate design entails the solution of an integral equation for the electric field in the cell using the method of moments (MoM). Our implementation is made efficient by using only very few design frequency points and accurately approximating a given filter transfer function by a quotient of polynomials as a function of frequency. Additionally, the problem impedance matrices are conveniently represented as the product of a material independent matrix and a vector of dielectric constants, thus allowing us to fill the matrices only once. Our code has been parallelized for the Cray T3D to take advantage of the intrinsic parallelization efficiencies offered by the GAs. Solutions are illustrated for a very narrow-band single-grating transmission filter and a relatively broad-band double grating reflection filter. Additionally, a solution for a five homogeneous layers Fabry-Perot filter is also presented.

Synthesis of novel all-dielectric grating filters using genetic algorithms

We are concerned with the design of inhomogeneous, all-dielectric (lossless) periodic structures which act as filters. The problem can be treated as an inverse problem. The authors begin by discussing scattering from a dielectric grating. The theory is used in the design of guided mode resonance filters.

C. Ditchman

Papers

Synthesis of novel all-dielectric grating filters using genetic algorithms

Synthesis of novel all-dielectric grating filters using genetic algorithms