Concentric Circular Antenna Array Research Articles

An optimal concentric circular antenna array design using atomic orbital search for communication systems

Abstract In this study, optimum radiation patterns of Concentric Circular Antenna Arrays (CCAAs) are obtained by using the Atomic Orbital Search (AOS) algorithm for communication spectrum. Communication systems stands as a nascent technological innovation poised to revolutionize the landscape of wireless communication systems. It distinguishes itself through its hallmark features, notably an exceptionally high data transmission rate, expanded network capacity, minimal latency, and a commendable quality of service. The most important issue in wireless communication is a precision antenna array design. The success of this design depends on suppressing the maximum sidelobe levels (MSLs) values of the antenna in the far-field radiation region as much as possible. The AOS, which is a rapid and flexible search algorithm, is a novel physics-based algorithm. The amplitudes and inter-element spacing of CCAAs are optimally determined by utilizing AOS to the reduction of the MSLs. In this study, CCAAs with three and four rings are considered. The number of elements of these CCAAs has been determined as 4–6–8, 8–10–12 and 6–12–18–24. The radiation patterns obtained with AOS are compared with the results available in the literature and it is seen that the results of the AOS method are better.

Hybridization of almost difference sets and DFT technique for concentric circular antenna array thinning

This paper introduces a hybrid methodology for minimizing the peak sidelobe level (PSLL) in concentric circular antenna arrays (CCAAs). Traditionally, the almost difference set (ADS) approach has been utilized for determining active element positions, but its effectiveness in PSLL reduction is limited. To address this limitation, the proposed methodology integrates the ADS approach with the discrete Fourier transform (DFT) technique. This integration optimizes excitation amplitudes for activated elements within the ADS-based thinned array, resulting in significant PSLL reduction. Simulation results across various case studies demonstrate that the hybrid ADS-DFT method achieves lower PSLL values than existing thinning techniques while maintaining high computational efficiency. Additionally, electromagnetic (EM) simulations validate the efficiency of the proposed method, considering mutual coupling effects.

Synthesis of Concentric Circular Antenna Array Employing Jaya Algorithm

In the present scenario, Sidelobe Level (SLL) is treated as the most important parameter of the antenna array as it assists in suppressing interference and adjacent noise in wireless communication systems. As the maximum SLL value examined higher power wastage in unwanted signal direction, a transmitter of the communication system encounters major hitches. In this article, the optimum design of four various groups of Concentric Circular Antenna Array (CCAA) of the array antenna has been to lower SLL as much as possible. Optimum beam pattern synthesis of the proposed array antenna has been carried out by optimizing the standardized current distribution of the array antenna elements, all elements placed with fixed inter-element spacing. The work proposed algorithm is the Jaya optimization algorithm, the main aim of this technique is to describe the credibility of a currently chosen human social behaviour-based optimization algorithm known as Jaya. This very easy algorithm with lower complexity to synthesize Concentric Circular Antenna Array (CCAA) which is thoroughly utilized in the present scenario communication systems. The obtained results of the Jaya algorithm compared with Particle Swarm Optimization (PSO) and previously published articles. The Jaya algorithm achieved an improved side lobe level reduction as correlated to the PSO algorithm, finally getting results to examine the improved ability of Jaya as the best suitable method and achieve better sidelobe level suppression.

Multi-objective sparse synthesis optimization of concentric circular antenna array via hybrid evolutionary computation approach

Sparse synthesis can reduce the maximum sidelobe level (SLL) and overhead of the concentric circular antenna array (CCAA) by switching off partial array elements. However, previous works have not considered finding a balance between the number of switched-on elements of CCAA and reducing the maximum SLL, or jointly optimizing the excitation current weights of array elements to further suppress the maximum SLL. In this work, we address these challenges by formulating a hybrid multi-objective optimization problem (MOP) with discrete and continuous solutions. To solve this hybrid NP-hard problem, we consider two approaches: the two-step and one-step methods. In the two-step method, we convert the original MOP into two subproblems and propose an enhanced non-dominated sorting genetic algorithm-II (ENSGA-II) and an improved genetic algorithm with new mutation and attraction (IGAnMA) to solve these two subproblems. ENSGA-II and IGAnMA involve the hierarchy mechanism and attraction operator to enhance the solving abilities, respectively. In the one-step method, we propose an improved hybrid non-dominated sorting genetic algorithm-II (IHNSGA-II) with global search and hybrid solution update methods to solve the MOP in one step. Numerical simulation results show that the proposed methods are effective and stable for the sparse synthesis of CCAA. Additionally, electromagnetic simulation results demonstrate the validity of the proposed approaches in a more practical environment.

A novel optimized conical antenna array structure for back lobe cancellation of uniform concentric circular antenna arrays

A novel optimized conical antenna array structure for back lobe cancellation of uniform concentric circular antenna arrays

Time-Efficient Multiplex Orbital Angular Momentum Beam Synthesis With Arbitrary-Shaped Array Using Multipole Moment Expansion

Despite the significant interest in pattern synthesis over the decades, the beam synthesis of orbital angular momentum (OAM) has received relatively little attention. In this paper, we present a time-efficient method for OAM beam synthesis based on multipole moment expansion. The approach introduces the multipole moment term as a transforming level, which separates the excitation coefficients and radiation pattern. We evaluate the performance of our proposed method through several examples and demonstrate its high capability to synthesize multiplex OAM beams with arbitrary-shaped arrays, ensuring reasonable accuracy. The theoretical analysis shows a significant improvement in computational efficiency and a great reduction in computational complexity compared to conventional synthesis methods. Finally, we design, fabricate, and measure a double-ring concentric circular patch antenna array using our proposed method, and the measured results confirm the validity of our approach. The work provides a valuable contribution to the field of OAM beam synthesis and offers a promising avenue for future research.

COSECANT-SQUARED BEAM PATTERN SYNTHESIS OF CONCENTRIC CIRCULAR ANTENNA ARRAY IN A RANGE OF AZIMUTH PLANE USING EVOLUTIONARY ALGORITHM

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 (φ=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.

Evolutionary Computation for Sparse Synthesis Optimization of CCAAs: An Enhanced Whale Optimization Algorithm Method

Concentric circular antenna arrays (CCAAs) can obtain better performance than other antenna arrays. However, high overhead and excessive sidelobes still make its application difficult. In this paper, we consider the sparse synthesis optimization of CCAAs. Specifically, we aim to turn off a specific number of antennas while reducing the sidelobe of CCAAs. First, we formulate an optimization problem and present the solution space. Then, we propose a novel evolutionary method for solving the optimization problem. Our proposed method introduces hybrid solution initialization, hybrid crossover method, and hybrid update methods. Simulation results show the effectiveness of the proposed algorithm and the proposed improvement factors.

Performance Investigation of Linearly Arranged Circular, Circular Planer, Rectangular, and Concentric Circular Antenna Arrays Using Robust NVL Techniques

In this research, linearly arranged circular antenna array (LCAA), linearly arranged circular planer antenna array (LCPAA), linearly arranged rectangular antenna array (LRAA), and linearly arranged concentric circular antenna array (LCCAA) are analyzed using robust techniques. These four antenna arrays are briefly investigated to evaluate their beam width performance, ability to detect a false signal, and SINR power pattern performances. Robust techniques—fixed diagonal loading (FDL), optimal diagonal loading (ODL), variable diagonal loading (VDL), and new variable loading (NVL) techniques—are applied, and the NVL technique is found to be superior and provides the best performance with the proposed LCCAA beamformer. With an SINR of 40.45 dB, 40.29 dB, 40.18 dB, and 39.99 dB for 0°, 1°, 2°, and 3° disparity angles, respectively, and output powers of −0.019 dB, −0.076 dB, and −0.171 dB for 1°, 2°, and 3° disparity angles, respectively, LCCAA beamformers using the NVL technique outperform other beamformers with different robust approaches.

Performance Analysis of Linearly Arranged Concentric Circular Antenna Array with Low Sidelobe Level and Beamwidth Using Robust Tapering Technique.

In this research, a novel antenna array named Linearly arranged Concentric Circular Antenna Array (LCCAA) is proposed, concerning lower beamwidth, lower sidelobe level, sharp ability to detect false signals, and impressive SINR performance. The performance of the proposed LCCAA beamformer is compared with geometrically identical existing beamformers using the conventional technique where the LCCAA beamformer shows the lowest beamwidth and sidelobe level (SLL) of 12.50° and -15.17 dB with equal elements accordingly. However, the performance is degraded due to look direction error, for which robust techniques, fixed diagonal loading (FDL), optimal diagonal loading (ODL), and variable diagonal loading (VDL), are applied to all the potential arrays to minimize this problem. Furthermore, the LCCAA beamformer is further simulated to reduce the sidelobe applying tapering techniques where the Hamming window shows the best performance having 17.097 dB less sidelobe level compared to the uniform window. The proposed structure is also analyzed under a robust tapered (VDL-Hamming) method which reduces around 69.92 dB and 48.39 dB more sidelobe level compared to conventional and robust techniques. Analyzing all the performances, it is clear that the proposed LCCAA beamformer is superior and provides the best performance with the proposed robust tapered (VDL-Hamming) technique.

Synthesizing of concentric circular antenna arrays by using a combination of ant lion optimizer and sequential quadratic programming

AbstractAntenna array synthesis is quite a popular topic in electromagnetics and finding suitable array parameter values is a challenging nonlinear engineering problem in this field. In recent years, it has been realized that optimization algorithms can be used to achieve desired solutions in this area. Besides, improvements in the optimization algorithms make it possible to perform synthesis processes on different array structures and to obtain better results. In this paper, a method based on a combination of ant lion optimizer (ALO) and sequential quadratic programming (SQP) is proposed for the concentric circular antenna array (CCAA) synthesis. Excitation amplitudes of array elements are optimized for CCAAs with low maximum sidelobe level (MSL), narrow first null beamwidth (FNBW), and low dynamic range ratio (DRR). The results of proposed ALO‐SQP method are compared with those of 11 different algorithms: ALO, moth flame optimizer (MFO), SQP, symbiotic organisms search (SOS), biogeography based optimization (BBO), opposition‐based gravitational search algorithm (OGSA), cat swarm optimization (CSO), firefly algorithm (FA), evolutionary programming (EP), backtracking search optimization algorithm (BSA), and seeker optimization algorithm (SOA). The comparisons indicate that the CCAAs synthesis using the proposed method presents good MSLs, FNBWs, and DRRs.

Synthesis of Concentric Circular Antenna Array Using Whale Optimization Algorithm

Through the ages the importance of the swarm intelligence-based algorithm has gained popularity in the field of optimization. The Whale Optimization Algorithm (WOA) is one such popular meta-heuristics nature inspired swarm intelligence-based algorithm which is well accepted for solving optimization problems, as it is simple and capable to obtain optimal results efficiently. In this paper, few benchmark functions along with radiation patterns of concentric circular antenna array are presented and their performance is optimized using WOA. Simulation results are shown by taking various benchmark functions, namely: Three hump & Six hump camel function, Ackley, Egg Crate Function, and Egg Holder Function. The capability of the WOA algorithm is also tested through pattern synthesis with respect to the thinned array as well as non-uniformly excited array for four diverse sets of CCAA geometries. When comparison is being done with respect to renowned and most popular optimization approaches like PSO, the WOA technique proves to be excellent in terms of maximum SLL suppression. Optimization results show the better capability of WOA in the field of optimization.

An optimal far field radiation pattern synthesis of mutually coupled antenna arrays

This article presents a precise approach for far-field radiation pattern (FFRP) correction of mutually coupled discrete dipole element (DDE) array of monopole antennas and concentric circular antenna array (CCAA) of dipole elements by employing the parametric assimilation technique (PAT). The effect of mutual coupling is a crucial part of any practical antenna array design issue. Various techniques have been suggested to calculate, compensate and reduce the mutual coupling effect during the last few decades. This article shows an exact method for mutual coupling inclusive corrected radiation pattern synthesis using PAT. The parameters of mutual impedance are calculated and assimilated with the values of the desired radiation pattern. The employed technique is cost-effective, less complex and easy to implement while achieving better performance for mutually coupled DDE array and CCAA synthesis. Grey wolf optimisation (GWO) is a state-of-the-art stochastic algorithm applied here to find the optimal values of the current amplitude excitation weights and the inter-element spacing between each element of the array in the DDE array and three-rings structure CCAA for the desired, uncorrected and corrected FFRP synthesis. Some well-established evolutionary optimisation techniques like particle swarm optimisation (PSO), differential evolution (DE) and social spider algorithm (SSA) are also employed in this article for the sake of comparison with the results achieved by using the GWO algorithm. Finally, the supremacy of GWO algorithm based design is demonstrated and validated by employing the 16-elements DDE array of monopole antennas and the three-ring CCAA of dipole elements.

An Efficient HAPS Cross-Layer Design to Mitigate COVID-19 Consequences

This paper proposes a new cross-layer communication system for the provision of Internet services and applications to mitigate the negative impacts of COVID-19, due to which the massive online demands are affecting the current communication systems’ infrastructures and capabilities. The system requirements and model are investigated where it utilizes high-altitude platform (HAP) for fast and efficient connectivity provision to bridge the communication infrastructure gap in the current pandemic. The HAP is linked to the main server or gateway station located on ground and can provide communication narrow beams towards isolated areas which suffer from poor terrestrial radio coverage or lack of communication infrastructure. The vital e-learning applications using Internet services provision from the proposed HAP system are described and modelled including system adaptation parameters such as the application and physical layers to control the data rates of different e-learning applications and the overall cell data rate. On the other hand, the provision of high-speed Internet services from the proposed system is supported by using adaptive antenna arrays onboard HAP which provides high-gain beams to achieve the required high-quality transmission data rates at the student premises and provides the capability of coverage cell area adaptation for load balancing. The concentric circular antenna arrays with tapered feeding are proposed in this adaptive antenna system to control the cell mainlobe gain and reduce the out-of-coverage radiation as well. In addition, the system feasibility has been proved in two coverage scenarios including single-beam and multibeam HAP communications.

Enhanced-Least-Mean Square Algorithm Based Weight Optimization for Concentric Circular Antenna Array

In the field of wireless communication, interfering signals impose critical problems during the transmission of signals. Signal to noise ratio can be improved at the base station by proper selection of array antenna. In this paper, Enhanced- Least- Mean Square algorithm has been presented to be employed for Concentric Circular Antenna Array as it has the ability to provide symmetrical beam pattern in all 360 degree with lesser effect of mutual coupling compared to other array patterns. Enhanced- Least- Mean Square algorithm is the algorithm for adaptive-beamforming that optimizes the weight vector such that the direction of the main beam of the circular antenna is adjusted, mitigating the undesired interfering signals thereby enhancing the desired signal. Mean-square error is minimized between the output received from the array and the reference signal due to optimal weight obtained from Enhanced- Least- Mean Square algorithm. The proposed algorithm incorporates iterative procedure as it does computation with the current weights for the processed signal, thereby generating deviation between the signal obtained from processing and the desired signal. This information about new error is utilized in adjusting the weights using gradient-method thereby obtaining the optimized weights. The simulation of the proposed algorithm is done using MATLAB, which converges at about 10 iterations. Performance evaluation is done for various angles of arrival for the proposed algorithm. Implementation of Enhanced- Least- Mean Square algorithm is simple comparable to other techniques as it eliminates inversion of any matrix.

Generation and numerical simulation of the focused OAM beams

The generation of the focused orbital angular momentum (OAM) beams using concentric uniform circular array (CUCA) is proposed in this paper. Since the ring shaped beams of the traditional electromagnetic (EM) vortex wave diverge along the propagation axis, only part of the beam is utilized for target detection, leading to a low efficiency. In this paper, two schemes are proposed to generate the focused OAM beams using concentric uniform circular antenna array (CUCA). Different from the traditional beam convergence method by reducing the divergence angle using parabolic reflector or lens, the proposed method employs a group of OAM beams with same divergence angle so that the superposed beam is focused at a certain azimuth angle. The feed amplitudes and phases of the elements of CUCA are firstly designed and validated using array factor multiplication. Then full wave simulations are conducted based on multilevel fast multipole algorithm (MLFMA) to calculate the radiation patterns and near field distributions of CUCA consist of micro strip patch antenna to further validate the proposed schemes. Simulation results indicate that the focused OAM beam can be achieved and the phase of the radiated field keeps the vortex property.

Synthesis of Cosecant-Squared Beam Patterns of Concentric Circular Antenna Array in a Range of Azimuth Plane Using Evolutionary Algorithm

Synthesis of Cosecant-Squared Beam Patterns of Concentric Circular Antenna Array in a Range of Azimuth Plane Using Evolutionary Algorithm

Optimal Synthesis of Concentric Circular Antenna Arrays Using Political Optimizer

In this study, political optimizer (PO) which has entered the literature as a novel socio-inspired meta-heuristic method is used to improve radiation properties of concentric circular antenna arrays (CCAAs) in the far field such as wireless communication of smart grids and Internet of things. The radiation pattern of far field is improved by reducing the sidelobe level (SLL), which is the most important parameter of the antenna radiation pattern. By reducing SLL, unwanted signals and interferences in the same frequency band are suppressed. PO is a novel global optimization method which is based on the multi-phased process of politics. The inter-element spacing and amplitude coefficients of concentric circular antenna array elements are determined optimally by PO algorithm to obtain a radiation pattern with a lower SLL value. To show the flexibility and performance of the proposed algorithm, three-ring CCAAs with different numbers of elements (4, 6, 8 elements and 8, 10, 12 elements) without and with the center element are synthesized. SLL values obtained by PO algorithm are compared with other recent optimization methods in the literature. The results obtained with PO algorithm in all comparisons show that it reached a lower SLL value than other optimization methods.

Beam steering using OAM waves generated by a concentric circular loop antenna array

Orbital Angular Momentum (OAM) is an attractive feature of electromagnetic waves that gains great research attention in several areas in radio and optics. This paper describes a superposition of OAM waves of different orders for single/multi-beam steering in the transverse direction in communication and radar-sensing applications. A new design of the antenna is proposed. The main body of the antenna consists of a concentric circular loop antenna array that is excited by a traveling wave current. This design overcomes some of the limitations challenging the use of multi-orders OAM waves in beam steering, in particular the need for placing more than one OAM-order generator in the same plane. The proposed method overcomes this limitation as many loops of different sizes could be simply placed in one plane. The feeder of the antenna, on another hand, is designed using two loops with one being a parasitic element. This parasitic element-based design shows great enhancement to the bandwidth allowing the antenna to serve over a wide range of applications. Various OAM mode groupings using the superimposed OAM waves are demonstrated here via theoretical calculations, and beamforming is validated with full-wave numerical simulations.

The optimal synthesis of thinned concentric circular antenna arrays using slime mold algorithm

ABSTRACT In this paper, thinned concentric circular antenna arrays (CCAAs) with low sidelobe levels and fixed half-power beamwidths are synthesized by using the Slime Mold Algorithm (SMA). SMA is a novel stochastic optimization method inspired by the oscillation mode of the slime mold in nature. Entering the literature as a new optimization technique, SMA is based on a matchless mathematical model that finds the most suitable way to find food in the search space thanks to the negative and positive oscillations of the slime mold. SMA is also used to obtain thinned CCAAs having different ring numbers. It is seen that the results obtained by SMA are very good. Besides, the flexibility of SMA in different values of parameters is a promising feature for the other antenna array synthesis problems. The results obtained by SMA are compared with several meta-heuristic algorithms in the literature. SMA shows a better performance in synthesizing CCAAs than the other compared algorithms.