Design Of Linear Antenna Arrays Research Articles

Using Bayesian Inference for Linear Antenna Array Design

Based on the observation that design and inference are both generalized inverse problems, we devise a new approach that uses the Bayesian inference framework for the automated design of linear antenna arrays. Compared to the optimization-based techniques that are widely used for automated antenna design, this newly-developed method has a prominent advantage, which is the capability to determine automatically the number of antenna elements required to satisfy design requirements and specifications. Three broadside array design problems, which include the null-controlled pattern, the sector beam pattern, and the Chebyshev pattern, along with an end-fire array design problem, are presented as examples. The obtained results demonstrate the advantages of using the Bayesian inference framework for the design of linear antenna arrays.

APPLICATION OF BOOLEAN PSO WITH ADAPTIVE VELOCITY MUTATION TO THE DESIGN OF OPTIMAL LINEAR ANTENNA ARRAYS EXCITED BY UNIFORMAMPLITUDE CURRENT DISTRIBUTION

This paper presents a new optimization technique for the design of linear antenna arrays. The proposed technique is based on a novel variant of PSO called Boolean PSO with Adaptive Velocity Mutation. The antenna arrays are optimized under requirements for maximizing the power gain at a desired direction and minimizing the side lobe level of the radiation pattern. The impedance-matching condition of all the array elements is also required by the algorithm. The optimization technique has been developed considering that the array elements are excited by uniform-amplitude current distribution. The radiation characteristics of the antenna array are extracted by using the method of moments. The technique has been applied in several broadside and non-broadside cases of collinear wire-dipole antenna arrays and seems to be capable of improving the radiation characteristics of the antenna arrays in practice.

Optimum Design of Linear Antenna Arrays Using a Hybrid MoM/GA Algorithm

Synthesis of arbitrarily shaped radiation patterns using linear antenna arrays has a significant importance in many applications. Many attempts based on analytical schemes are exerted for this purpose. However, these analytical methods are developed for specific problems, and usually synthesis of the radiation pattern is subject to only one restriction. On the other hand, optimization algorithms are utilized for more general problems. However, these algorithms require more computational time. In this letter, a new hybrid technique for synthesizing arbitrary-shaped radiation pattern using a linear array is developed. The algorithm is based on a combination between the method of moments (MoM) and the genetic algorithm (GA). The proposed algorithm is applied to synthesis of both symmetric and asymmetric radiation pattern distributions with minimum number of elements. Excellent agreement is obtained by comparison to other analytical and optimization techniques.

Linear antenna array synthesis with modified invasive weed optimisation algorithm

Linear antenna array design is one of the most important electromagnetic optimisation problems of current interest. This article describes the application of modified version of a recently developed metaheuristic algorithm, known as the invasive weed optimisation (IWO), to optimise the spacing between the elements of the linear array to produce a radiation pattern with minimum side lobe level and null placement control. IWO is a novel ecologically inspired algorithm that mimics the process of weeds colonisation and distribution and is capable of solving general multi-dimensional, linear and non-linear optimisation problems with appreciable efficiency. For this application, we modified the classical IWO by introducing a more explorative routine of changing the mutation step-size with iterations. Three design examples are presented that illustrate the use of the IWO algorithm, and the optimisation goal in each example is easily achieved. The results of the modified IWO algorithm have been shown to meet or beat the results obtained using other state-of-the-art metaheuristics like the classical IWO, genetic algorithm (GA), particle swarm optimisation (PSO), memetic algorithms (MA), and tabu search (TS) in a statistically meaningful way.

Design and Implementation of Embedded Printed Antenna Arrays in Small UAV Wing Structures

Unmanned aerial vehicles (UAV) are extensively being used in exploration, surveillance and military applications. Such vehicles often collect data via special sensors and send the data back to the central station via wireless links. Embedded in wing structure printed antennas will eliminate the drag due to friction, and allow for extended load capability due to their extra light weight. In this work we present the design and implementation of a 4-element linear antenna array embedded in a small UAV wing structure. The antenna array operates in the 2.4 GHz ISM band. Simulations and measurements that characterize the performance of the antenna array are presented. Field measurements show the impact of utilizing beam-forming in enhancing the communication link throughput.

DESIGN OF TIME-MODULATED LINEAR ARRAYS WITH A MULTI-OBJECTIVE OPTIMIZATION APPROACH

This article proposes a Multi-objective Optimization (MO) framework for the design of time-modulated linear antenna arrays with ultra low maximum Side Lobe Level (SLL), maximum Side Band Level (SBL) and main lobe Beam Width between the First Nulls (BWFN). In contrast to the existing optimization-based methods that attempt to minimize a weighted sum of SLL, SBL, and BWFN, we treat these as three distinct objectives that are to be achieved simultaneously and use one of the best known Multi- Objective Evolutionary Algorithms (MOEAs) of current interest called MOEA/D-DE (Decomposition based MOEA with Difierential Evolution operator) to determine the best compromise among these three objectives. Unlike the single-objective approaches, the MO approach provides greater ∞exibility in the design by yielding a set of equivalent flnal solutions from which the user can choose one that attains a suitable trade-ofi margin as per requirements. We compared time-modulated antenna structures with other methods for linear array synthesis such as the excitation method and the phase-position synthesis method on the basis of the approximated Pareto Fronts (PFs) yielded by MOEA/D-DE and the best compromise solutions determined from the Pareto optimal set with a fuzzy membership- function based method. The flnal results obtained with MOEA/D-DE were compared with the results achieved by two state-of-the-art single objective optimization algorithms and flve other MO algorithms. Our simulation studies on three instantiations of the design problem re∞ect the superiority of the MOEA/D-DE based design of time-modulated linear arrays.

Linear Retro-Directive Antenna Array Using 90<formula formulatype="inline"><tex>$^{\circ}$</tex></formula> Hybrids

A novel approach is developed to design linear passive retro-directive antenna arrays by properly making use of 90deg hybrids. For a 90deg hybrid, when its direct port and coupled port are terminated with the same reflection coefficient, the phase difference of the reflected signals at the other two ports are reversed to that of the incident signals. This then becomes to be a phase difference reversal circuit (or a retro-directive circuit) and leads to the design of linear retro-directive antenna arrays using 90deg hybrids. The formulas and a folding method on designing linear retro-directive array circuits with arbitrary element numbers are presented with the measurement results of three-element, four-element, and six-element retro-directive antenna arrays.

Bees algorithm for design of dual-beam linear antenna arrays with digital attenuators and digital phase shifters

This article describes a method of designing a reconfigurable dual-beam linear antenna array using bees algorithm (BA). The BA is an optimization algorithm inspired by the behavior of the honey bees to find the optimal way of harvesting food resources around the hive. The proposed method is very simple and can be used directly in practice to synthesize multiple beam antenna arrays with digital attenuators and digital phase shifters. A good agreement between the desired pattern and the synthesized pattern using BA is obtained. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.

Linear Antenna Array Synthesis Using Taguchi's Method: A Novel Optimization Technique in Electromagnetics

We describe a new global electromagnetic optimization technique using Taguchi's method and apply it to linear antenna array design. Taguchi's method was developed on the basis of the orthogonal array (OA) concept, which offers systematic and efficient characteristics. This paper illustrates the implementation procedure of Taguchi's method in electromagnetic optimization problems. The optimization procedure is then used to design two linear antenna arrays with specific array factor requirements. Obtained results show that the desired null controlled pattern and sector beam pattern are successfully achieved. Compared to traditional optimization techniques, Taguchi's method is easy to implement and efficient to reach the optimum solutions

Design of Fully Digital Controlled Reconfigurable Array Antennas with Fixed Dynamic Range Ratio

In this paper, we propose an optimization method based on Genetic Algorithm (GA) for design of reconfigurable dual-beam linear isotropic antenna arrays with phase only control of digital phase shifters. The problem is to find a fixed amplitude distribution using four-bit digital attenuator that will generate two broadsided symmetrical beams in vertical plane: a pencil beam with zero phases and a flat-top beam with discrete phases of a five-bit digital phase shifter, with or without pre-fixing the dynamic range ratio (I max /I min) of excitation amplitude distribution to a value equal to or less than seven.

A multi-objective approach in the linear antenna array design

We show that linear antenna array design can be modeled as a multi-objective optimization problem. A genetic algorithm is proposed for the solution of this problem. This genetic algorithm efficiently computes the trade-off curve between main beam width and side lobe level for linear antenna arrays with uniform and non-uniform separations. For uniform separation, the proposed algorithm is validated against the Chebyshev method for the cases of 6-, 8-, 10-, and 12-element linear arrays. Simulation results for non-uniform spacing with uniform and non-uniform excitations applied across the array indicate that the trade-off curve between main beam width and side lobe level for uniform spacing arrays can be improved by introducing non-uniform spacing.

Multiple-pattern linear antenna arrays with singleprefixed amplitude distributions: modifiedWoodward-Lawson synthesis

The authors describe the design of linear antenna arrays that generate multiple radiation patterns by switching between different excitation phase distributions while maintaining a constant pre-established amplitude distribution. Examples are given of antennas with uniform or Gaussian amplitude distributions that, depending on their phase distribution, generate a sum pattern, a flat-topped beam or a cosec-squared pattern.

First- and second-order characterization of direction dispersion and space selectivity in the radio channel

We present analytical results relating to first- and second-moment characterization of direction dispersion and spatial selectivity in the radio channel as well as to the duality between these two effects. Dispersion in direction can be characterized either by the direction power spectrum or by a family of spatial Doppler power spectra at the reception site. Two measures called the direction spread and the maximum spatial Doppler spread are introduced which describe the extent of channel dispersion in direction and in spatial Doppler frequency, respectively. Both measures are analogous to the delay and Doppler spreads, which are commonly employed to describe the extent of dispersion in delay and Doppler frequency, respectively. The relationships between the two approaches for characterizing spatial dispersion and especially between the direction and maximum spatial Doppler spreads are analytically established. The coherence distance at a certain level summarizes certain features of space selectivity in the radio channel which impact on the performance of communication systems. Two uncertainty relations between the direction spread and the coherence distance as well as between the maximum spatial Doppler spread and the coherence distance express the duality between direction dispersion and space selectivity. These relations are analogous to those established previously between the delay spread and the coherence bandwidth and between the Doppler spread and the coherence time. Examples relevant to mobile communications in the case where the waves propagate only horizontally illustrate the theoretical results. An application of these results to the design of uniform linear antenna arrays is also discussed.

Linear antenna array design with partial adaptivity

The paper presents a new approach to the design of a uniform linear array with partial adaptivity. The technique uses the symmetric and skew-symmetric eigenvectors of a certain symmetric Toeplitz matrix to form the fixed weighting vector for the main beam and the transformation matrix for the cancellation beam. This approach allows the adaptive dimension of the processor to be reduced to about half of that of the full processor without prior knowledge of the interference field. Eigendecomposition is performed on matrices of dimensions that are half that of the number of elements. Numerical results show that the new approach is effective in designing partially adaptive uniform linear arrays.