Search

This paper proposes the design of virtual antenna arrays with frequency diversity for radar systems in fifth-generation flying ad hoc networks. These virtual arrays permit us to detect targets from the sky with flying drones. Each array element is composed of a microstrip antenna mounted on quadcopter drones and is virtually connected with the other elements. The antennas are tuned to work at the lower fifth-generation frequency band of 3.5 GHz. The design process considers the optimization of frequency offsets and positions for each element to obtain a side lobe level reduction. This methodology is carried out by particle swarm optimization. Several design examples are presented with random frequency offsets and non-uniform positions. These designs are compared to uniform-spaced arrays excited with Hamming frequency offsets. The simulation results show that using random frequency offsets and non-uniform positions provides a minor side lobe level reduction. This research demonstrates the feasibility of using virtual arrays for radar systems in fifth-generation flying ad hoc networks. [ABSTRACT FROM AUTHOR]

This work is concerned with the methodology for improvement of the radiation pattern performance and eliminating the effect of unwanted interference of symmetric time modulated linear antenna array (STMLAA) in the predefined direction. This is achieved using evolutionary technique called Novel Particle Swarm Optimization with Wavelet Mutation (NPSOWM) for various application specific optimization like SLL only reduction, dual broad null and multiple broad null optimization. The optimized results obtained by using NPSOWM are validated by CST-MWS by captivating practical elements of dipole antenna and its array configuration. The numerical results show the effect of the particular (practical) antenna on the array. Various examples have taken for this purpose. A set of 16-element antenna array have designed for SLL only reduction. 16-, 32-, and 64-element STMLAA for incorporating the dual broad nulls in the angular range from 400 to 700 over the elevation plane. A set of 24-, 30-, and 32-element antenna array have occupied for multiple broad nulls. The strength of the adopted algorithm is tested for different number of array antenna configuration, which establish the efficacy of the optimization technique NPSOWM adopted for achieving the interference cancellation in the predefined direction and performance improvement of the antenna array such as simultaneous improvements of broad nulls (BNs), sidelobe level (SLL), sideband level (SBL), and the directivity. From the simulated results it is clear that NPSOWM can perform better than that of un-optimized linear antenna array with respect to BNs, SLL, and SBLs and Directivity. [ABSTRACT FROM AUTHOR]

This paper applies time modulation to deal with the design of antenna arrays for UAVs formation flight using a rectangular micro-strip as antenna element in the frequency of 2.4 GHz. The motivation for this paper is to exploit the properties and advantages of time-modulated arrays in an interesting application: UAVs formation flight. This design considers the optimization of the position of the drones (or antenna elements) and the time switched sequences of the elements in a linear geometry. The design process to find the optimal positions of the drones for flight formation and the switch-on interval of each element is carried out by means of the methods of Particle Swarm Optimization and Invasive Weed Optimization. The main contribution to the field of this paper is a performance evaluation of the design problem for UAVs-based linear antenna arrays considering time modulation in terms of side lobe level (SLL) and sideband levels (SBLs). Simulation results are provided in terms of SLL, SBLs, switching time and positions of the drones. These simulation results illustrate that the time modulation could provide a SLL improvement with respect to previous results in literature. [ABSTRACT FROM AUTHOR]

This paper presents a design of fractal antenna arrays based on circular arrays of circular subarrays for scannable pattern using rotational symmetry properties of the complex feeding excitations for a maximum performance in terms of side lobe level (SLL) and directivity (DIR). This fractal array design considers the optimization of the amplitude and phase excitations exploiting the fractal characteristics of the geometry (rotational symmetry) in order to generate a scannable pattern. The synthesis process is carried out by the method of Differential Evolution (DE). The main advantages of using rotational symmetry are that the optimal excitations for a particular beam steering angle could be applied to other beam steering angles remaining in the same array factor characteristics (SLLand directivity) for every beam steering angle. This design of fractal antenna arrays provides a complete scanning of the azimuth plane with optimal characteristics of the radiation pattern using just one optimal design vector of amplitude and phase excitations. Furthermore, the performance of the fractal antenna array optimized with DE is compared with respect to the cases of Genetic Algorithms (GA), Particle Swarm Optimization (PSO), and the conventional progressive phase for the same array geometry. [ABSTRACT FROM PUBLISHER]

This paper reports a new research in the field of the timed antenna arrays. It is presented as a novel synthesis of timed antenna arrays for flat-top energy patterns. The synthesis is carried out by optimizing true-time delays and amplitudes of different pulsed antenna arrays. Specially, the study regards the linear array, uniform square array, and uniform concentric ring array geometries. The optimization process is carried out by the well-known sequential quadratic programming. This methodology is compared with the particle swarm optimization algorithm in terms of computational cost and the quality of solution. The results show the performance of different timed antenna arrays with optimum flat energy patterns. The mutual coupling effects are included by a full-wave simulation of Vivaldi elements for the timed linear array in order to verify the proposed method. Important remarks are given for the design of timed antenna arrays for a flat-top energy pattern. [ABSTRACT FROM AUTHOR]

This research presents the synthesis of the concentric ring antenna arrays for a wide coverage pattern. The synthesis process is formulated as an optimization of the antenna excitations. Harmony search algorithm and particle swarm optimization are implemented for this optimization problem. The antenna array considers disk patches at the L-band. First, the synthesis regards the behavior of the antenna array modeled by the cavity model. Second, the mutual coupling is included by using the full wave simulation. This synthesis could be very useful in satellites with terrestrial global coverage. The obtained antenna array provides a wide uniform power density and reduces considerably the hardware complexity for a satellite antenna system. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper presents a synthesis of a volumetric ring antenna array for a terrestrial coverage pattern. This synthesis regards the spacing among the rings on the planes X-Y, the positions of the rings on the plane X-Z, and uniform and concentric excitations. The optimization is carried out by implementing the particle swarm optimization. The synthesis is compared with previous designs by resulting with proper performance of this geometry to provide an accurate coverage to be applied in satellite applications with a maximum reduction of the antenna hardware as well as the side lobe level reduction. [ABSTRACT FROM AUTHOR]

This report presents a novel design of concentric ring antenna array for a reconfigurable isoflux pattern. The array considers 61 disk patch antennas including mutual coupling by using the cavity model at the frequency of 2.8 GHz. The problem consists in finding out a few levels of excitations for the disk patch antennas. Harmony search algorithm and particle swarm optimization are implemented for this optimization problem. This novel design permits to reduce the complexity of the antenna hardware in the whole antenna system mounted in a satellite, where the volume occupation and heat dissipations are critical issues. [ABSTRACT FROM PUBLISHER]

Abstract: The design of beam-forming networks (BFNs) for a multibeam-steerable antenna array using Coherently Radiating Periodic Structures (CORPS) in cellular mobile communication systems is presented. In this paper, the CORPS technology is introduced and applied to the design of beam-forming networks in cellular systems for the first time. The CORPS-BFNs proposed show improved performance over the common way to feed antenna arrays used in mobile systems. In this design, the input ports of the feeding network design are optimized using the particle swarm optimization (PSO) algorithm. Two 2-beam design configurations of CORPS-BFN for a multibeam-steerable linear array on a cellular scenario are proposed and analyzed. Simulation results show the benefits of BFNs based on CORPS on a cellular mobile scenario based on the array factor response, in terms of side lobe level (SLL) and signal-to-interference (SIR) improvement capability. Furthermore, results for average SIR improvement, signal to interference plus noise power ratio (SINR) and BER are discussed. [Copyright &y& Elsevier]