Array Design Problem Research Articles

COMBINED STRATEGIES BASED ON MATRIX PENCIL METHOD AND TABU SEARCH ALGORITHM TO MINIMIZE ELEMENTS OF NON-UNIFORM ANTENNA ARRAY

The minimization of elements in a non-uniform antenna array is critical in some practical engineering applications such as satellite and mobile communications. However, due to the complexity in the synthesis of an antenna array, the available techniques are not equally successful for reducing the element number of a non- uniform antenna array with as few elements as possible with respect to both solution quality and solution e-ciency. In this point of view, a combined strategy based on the matrix pencil method and tabu search algorithm is proposed with the goal of integrating the advantages of the high solution e-ciency of the matrix pencil method and the strong global searching ability of the tabu search algorithm when solving an antenna array design problem. In the proposed strategies, the desired radiation pattern is flrstly sampled to form a discrete pattern data set. The matrix pencil method is then employed to optimize the excitations

Optimization methodology for designing 2-CPAs exploiting pattern diversity in clustered MIMO channels

Arrays designed for multiple-input multiple-output (MIMO) communication systems must provide good performance in terms of information theoretic and microwave theoretic performance measures for a large number of channel scenarios. Consequently, the general MIMO array design problem is challenging. This paper proposes a novel optimization methodology for designing circular patch arrays (CPAs), under a clustered MIMO channel model assumption. Based on the ergodic capacity, it is found that the single-cluster scenario can approximate CPA performance in clustered channels, reducing the number of channel scenarios that need to be considered. Using a new definition of channel spatial correlation that allows for pattern diversity, metrics are derived for evaluating average and outage capacity performance of CPAs, which can be expressed as a function of only the antenna parameters. With this expression, an optimization is formulated and solved numerically for optimizing the parameters of a 2-CPA on a capacity based objective function and microwave theory performance constraints. An example design is given corresponding to a 2-CPA in the 2.4 GHz unlicensed frequency band.

Synthesis method of series-fed microstrip antenna arrays

A method for non-uniformly spaced series-fed rectangular microstrip array synthesis is given. By this approach the problem of patch array design turns out to be slot array synthesis. The resulting equivalent configuration gives the necessary parameters for the microstrip array geometry. Applications on Taylor, Bayliss and shaped-beam patterns show the validity of the method.

Cramer-Rao bounds for antenna array design

We study the impact of the geometry of the (planar) antenna array on the accuracy of the estimated direction(s) of arrivals of an emitting source. We develop explicit Cramer-Rao bounds (CRBs) of the azimuth and elevation angles that show a simple structure. In particular, for a fixed elevation angle, the CRBs are cosine functions of the source azimuth, and so, regardless of the array geometry. The amplitude and extremes of these functions depend on the array geometry. Hence, the array configuration can be chosen in order to ensure a desired (an)isotropic behavior. To do so, we propose a pragmatic methodology that also takes into account the array ambiguity problem. The array design problem is simplified by limiting the array search within a family of V-shaped arrays that are advantageously characterized by a single parameter, the angle between the two branches. A performance measure is proposed, then analytically expressed, to assess the array directivity and gain with respect to the more standardly used uniform circular array.

A fuzzy approach to the convective longitudinal fin array design

This work considers an optimum design problem for the longitudinal fin array with constant heat transfer coefficient in a fuzzy environment, where rigid requirements to strictly satisfy the total fin volume and array width and maximize the heat dissipation rate are softened. The proposed method shows that the fuzzy fin array design problem can be converted into a regular min–max type optimization problem by employing the tolerance approach. An entropic regularization technique is then applied to solve the resulting optimization problem. Some computational results are presented to illustrate the theory and solution procedure. A comparison of results from the regular non-fuzzy optimal model and the fuzzy model is also included.

Planar Slotted Waveguide Array Design Using the Multiport Technique

ABSTRACT One of the most important features of the Canadian Radarsat synthetic aperture radar satellite is the 15m.*1.5m. deployable, phase-scanned antenna. This paper will describe the design features of that antenna, with particular emphasis on the special techniques that have been developed to analyze and synthesize large slotted waveguide planar arrays. First, the multiport approach to slotted waveguide array design will be introduced. Both the hardware implementation, with its special test fixture, and the underlying analytical algorithms will be described. The latter algorithms make it possible to analyze the slotted structure taking into account all important mutual coupling effects, and to compute the optimal slot geometries. The new approach highlights features of the planar array design problem that have not been evidenced with earlier treatments. Moreover, in the case of a satellite antenna, the method lends itself to rigorous predictions of the r.f. performance in the space environment. The performance of the Radarsat EBB (Engineering Bread-Board) and Flight models has been verified by an intensive series of radiation pattern measurements, using the spherical and planar near-field techniques. This work has served to validate the multiport algorithms. The Radarsat approach to SAR antenna design is based around thin-wall flangeless aluminum waveguide technology. Extensions of the concept provide for dual polarization and dual frequency bands.

Travel time tomography simulations for the test ocean constructed for the 124th Meeting of the Acoustical Society of America

Geometric rays were traced for a variety of source–receiver configurations in the test ocean sound-speed field constructed for the 124th Meeting of the Acoustical Society of America. A stochastic inverse incorporating the statistical information distributed with the test ocean was performed using only one-way travel times as data. Realistic errors in travel times and source–receiver positions were allowed for. The travel times were assumed to be contaminated with internal-wave-induced travel time fluctuations. The fluctuation variance increased linearly with range, with a magnitude of 10 ms rms at 1000 km. This internal wave noise can be reduced by a factor of N−1/2 by assuming that the mesoscale sound-speed structure remains static over N internal-wave-induced decorrelation times. Decorrelation times shorter than 10 min have been observed in the North Pacific at 1000-km range, so a daily average can yield a net contamination below 1 ms, neglecting the effects of longer period fluctuations like internal tides. The simulation results are sensitive to the size of the assumed error, and using values below 1 ms can lead to unrealistically good performance. The size of the source–receiver position errors can vary dramatically depending on the navigational techniques used and can have significant effects on the array design problem. These sensitivities will be explored in the process of choosing a source–receiver array adequate to resolve 96% of the sound-speed variance at 700-m depth in the test ocean.

Solving a large nonlinear programming problem on a vector processing computer

In an earlier paper, the authors formulated an acoustic antenna array design problem as a nonlinear program. Computation times for large problems (about 400 sensors) were in the range of 8 to 10 hours on a Vax 11/780. Most of this time was spent in computing the objective function and its gradient. This paper describes how these computations (and these only) were recoded to exploit the vector processing capabilities of a Cray 1-M computer. Run times are reduced to less than one minute. The results have implications for many nonlinear programs whose function evaluations are very time consuming.

Design of optimum sonar transducer arrays using goal programming

The design of acoustic antenna arrays often involves the satisfication of multiple, conflicting design specifications. The use of conventional mathematical programming techniques in this endeavor have been inhibited by their inability to consider these multiple objectives within their design formulations. Most present techniques formulate the design problem in terms of a single objective subject to a set of design constraints which become difficult, if not impossible, to solve if these constraints are conflicting in nature. Goal Programming is an effective alternative methodology. Array pattern synthesis through Goal Programming provides the optimal solution to the multiple criteria design of various classes of acoustic antenna arrays. The design problems are formulated in terms of the multiple objectives expressed by the system response functions and the desired characteristics of the design parameters. The solution of two reasonably complex planar array designs is presented. The details of their formulation and solution provide an indication of the ability of this approach to resolve even more complex array design problems. [Work supported by Naval Sea Systems Command Code 0342.]