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This paper presents, a pattern synthesis method based on Differential Evolutionary Algorithm. A cosec² beam pattern has been generated from different concentric circular ring arrays of isotropic elements by finding the optimum set of elements amplitude and phase using the Differential Evolution algorithm. The shaped beam pattern (cosec²) is generated in three predefined azimuth planes (f=0°, 5° and 10°) from a Concentric Circular Antenna Array (CCAA) having two rings, three rings, and four rings. The total number or isotropic elements are equal for array geometries. The optimum excitation for array geometries is also verified for a range of arbitrarily chosen azimuth planes. The obtained main beam is similar to the desired pattern with some minor variations in peak Side Lobe Level (peak SLL) and ripple. Dynamic range ratio (DRR) is improved by using 4-bit discrete Amplitudes and 5-bit discrete Phases. These discrete excitations also simplify the design complexity of the feed networks. [ABSTRACT FROM AUTHOR]

This article proposes a method which generates a set of weights to synthesize sum or difference pattern with precisely controlled sidelobe level (SLL), null, and dynamic range ratio (DRR) for arbitrary arrays. Our pattern synthesis approach reduces mutual coupling (MC) between the neighboring elements and complexity of the feeding network design. However, the formulated optimization problem is nonconvex due to the nonconvex objective function and fractional DRR constraint. To tackle it, we first introduce two sets of auxiliary variables: one for DRR constraint and the other for sidelobe and null constraints. By doing so, we then decompose the original optimization problem into three sets of subproblems characterized by the auxiliary variables and weight variables. To facilitate the subproblem with weight variables reaching its optimum values, we derive an appropriate range of step size. Finally, we iteratively solve these subproblems to obtain the solution to the original problem. Extensive experiments employing non-equispaced linear and rectangular arrays, concentric ring array, and cylinder array, are implemented to demonstrate that the developed approach can accurately control SLLs, null and DRR for arbitrary arrays. [ABSTRACT FROM AUTHOR]

The number of elements reduction in different antenna array configurations such as linear, circular, rectangular, planar, and non-planar is of main concern for several research groups. This minimizes the complexity of the feeding network in static antenna arrays, whereas, in adaptive antenna arrays, it reduces the number of active components. The main issue in the array synthesis is to preserve the radiation pattern with minimum distortion compared to the original pattern. These issues are addressed by many researchers in linear, planar, and concentric circular arrays, but no attempt is made in the synthesis of uniform circular antenna arrays (UCAAs) that have elements distributed on a single circle. This is because the synthesis is almost performed in one plane where the radiation patterns in other planes are not predicted. In this paper, most of the aforementioned challenges are treated; the number of elements is reduced, the radiation pattern has minimum distortion, and the radiation pattern is symmetric in all array orthogonal planes. This is performed by dividing the original UCAA’s 3D radiation pattern into a suitable number of 2D plane patterns, each of which is separately synthesized using the specified number of elements. The 2D pattern synthesis process for a particular plane is confined to estimating a new set of non-uniform excitation coefficients while keeping the original UCAA’s array radius. To construct the final set of synthesized excitation coefficients for the 3D array pattern synthesis, we aggregate all of the estimated sets of excitation coefficients and take the average. To verify the efficacy of the proposed technique, the original and synthesized arrays are realized using the CST Microwave Studio using $\lambda \mathord {\left /{ {\vphantom {\lambda 2}} }\right. } 2$ dipole elements. The results indicated that substantially matched patterns were obtained. Furthermore, the coupling between the synthesized array elements is decreased, which enhances the radiation efficiency and realized array gain.

This paper extends the semidefinite relaxation (SDR) method to be capable of synthesizing linearly polarized shaped patterns with accurate control of sidelobe level (SLL), cross-polarization level (XPL), and dynamic range ratio (DRR) of the excitation distribution for arbitrary antenna arrays. In addition, by using the vectorial active element patterns, mutual coupling and platform effect can be also incorporated into the proposed vectorial shaped pattern synthesis. Three examples for synthesizing linearly polarized patterns with different pattern shape requirements and different antenna array geometries have been conducted to check the effectiveness and robustness of the proposed method. Compared to the original vectorial shaped pattern synthesis without DRR control, the proposed method with the DRR control can significantly reduce the obtained DRR which is very useful in many antenna array applications.

• The proposed algorithm takes the power gain pattern instead of the beam pattern as the cost function. As a result, it can obtain a higher minimum power gain in a wide-beam mainlobe. • The proposed algorithm can well control the dynamic range ratio (DRR) of the excitation amplitude to obtain the desired sidelobe level (SLL) for a wide-beam. • The proposed algorithm can solve the synthesis optimization problem with the close-form solution. In such a way, it is computationally effective. The paper maximizes the minimum power gain in a wide-beam mainlobe when satisfies both the desired sidelobe level (SLL) and the array excitation dynamic range ratio (DRR). We, firstly, set up the power gain pattern synthesis (PGPS) problem with mianlobe/sidelobe constraints and DRR constraint. With the aid of two introduced auxiliary variables, the non-convex mainlobe/sidelobe constraints are converted into linear forms. Then, these two linear constraints are written into the cost function to construct an augmented Lagrangian function of the primal optimization problem. A penalty dual decomposition based approach, which iteratively solves the primal variables in the inner loop and the dual variables in the outer loop, is proposed. The proposed algorithm estimates the power-gain-related variables and the SLL-related variables in a pseudo-analytical way while optimizing the array excitation by solving a constrained least square problem. Both linear array and planar array are simulated to assess the effectiveness and superiority of the proposed algorithm on DRR control issue by comparing it with the existing DRR reduction algorithms. Numerical results show that the proposed algorithm can obtain the highest minimum power gain in the wide-beam when satisfies both the desired SLL and the desired low DRR. [ABSTRACT FROM AUTHOR]

A method based on constricted Particle Swarm Optimization (CPSO) algorithm to design a non-uniformly spaced collinear array of thin dipole antennas of unequal height is proposed. This paper presents a method for computing the appropriate excitation and geometry of individual array elements to generate a pencil beam in the vertical plane with minimum Standing Wave Ratio (SWR) and fixed Side Lobe Level (SLL). Coupling effect between any two collinear center-fed thin dipole antennas having sinusoidal current distributions is analyzed using induced EMF method and minimized in terms of SWR. DRR of excitation distribution is fixed at a lower value for further mitigation of the coupling effect. Phase distribution for all the elements is kept at zero degree for broadside array. Optimization results show the effectiveness of the algorithm for the design of the array. Moreover method seems very conducive for estimating the mutual impedance between any two collinear center-fed thin dipole antennas having sinusoidal current distributions.

Reconfigurable antenna arrays are often capable of radiating multiple patterns by altering the excitation phases of the array elements. In this paper, an efficient method based on FFT is presented for generating dual-radiation pattern from a single rectangular planar array by modifying the excitation phases of the array elements while sharing common amplitudes. The common amplitudes shared by both the patterns and the phases which play the role of turning between the two patterns when updated over zero phase among the elements are computed using Self-adaptive Differential Evolution (SaDE) algorithm. Two different beam-pairs of pencil/pencil and pencil/flat-top are generated from the proposed array while maintaining precise design specifications. The proposed method greatly reduces the computational time as compared with the conventional method for calculating beam patterns. The dynamic range ratio of the excitation amplitudes are kept below a threshold level to reduce the design complexity of the attenuators at the feed network level and to minimize the effect of mutual coupling among the array elements. To illustrate the effectiveness of SaDE, the fitness functions associated with the two beam-pairs are minimized individually using differential evolution (DE) algorithm and particle swarm optimization (PSO) algorithm. Results clearly show the superiority of SaDE over DE and PSO to handle the proposed problem. [ABSTRACT FROM AUTHOR]