Design of thinned fractal antenna arrays for adaptive beam forming and sidelobe reduction

El‐Khamy, Said E.; Eltrass, Ahmed S.; EL-Sayed, Huda F.

doi:10.1049/iet-map.2017.0464

Cited by 24 publications

(14 citation statements)

References 25 publications

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“…Finally, the designed antenna elements are aligned to build 2 × 2 array antenna structure. In [199], a new antenna array is designed to to combine multi-band [200] features of thinned fractal antenna arrays with the adaptive beam forming requirements. In [201], a decoupling metamaterial (MTM) configuration based on fractal EMBG structure is presented to enhance the isolation between transmitting and receiving antenna elements in a closely packed patch antenna array.…”

Section: Fractal Array Antennasmentioning

confidence: 99%

Fractal antennas and arrays: a review and recent developments

Karmakar

2020

Int. J. Microw. Wireless Technol.

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In mathematical definition, a fractal is a self-similar subset of Euclidean space whose fractal dimension strictly exceeds its topological dimension which in turn involves a recursive generating methodology that results in contours with infinitely intricate fine structures. Fractal geometry has been used to model complex natural objects such as clouds coastlines, etc., that has space-filling properties. In the past years, several groups of scientists around the globe tried to implement the structure of fractal geometry for applications in the field of electromagnetism, which led to the development of new innovative antenna configurations called “fractal antennas” which is primarily focused in fractal antenna elements, and fractal antenna arrays. It has been demonstrated that by exploiting the recursive nature of fractals, several marvellous kinds of properties can be observed in antennas and arrays. The primary focus of this article is to provide a compressed overview of the developments in fractal-shaped antennas as well as arrays over the last few decades where the most prominent contributions mostly from IEEE journals have been highlighted. The open intention of this review work is to show an encouraging path to antenna researchers for its advancement using fractal geometries.

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Section: Fractal Array Antennasmentioning

confidence: 99%

Fractal antennas and arrays: a review and recent developments

Karmakar

2020

Int. J. Microw. Wireless Technol.

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“…Another part of the research related to BF concerns evolutionary optimization methods [20]- [28]. A BF method is pro-posed in [20] by using an evolutionary method called invasive weed optimization (IWO).…”

Section: Prior Artmentioning

confidence: 99%

“…A hybrid method that integrates interval analysis and PSO is applied in [26] and [27] to implement BF in linear antenna arrays. Finally, a combination of the ant colony optimization and the least mean squares algorithm is proposed in [28] to perform BF and also to achieve a low SLL in thinned fractal antenna arrays. All these evolutionary methods are really effective in a stable or slowly changing electromagnetic environment.…”

Section: Prior Artmentioning

confidence: 99%

“…The great difficulty in solving this problem is that the feeding weights must be calculated again and again in real time and every time when changes occur in DoA of a DIS or in DoA of a UIS. In such ever-changing environments, evolutionary optimization methods [20]- [28] are not practically useful, because they need much time to give a solution due to their iterative structure. Of course, there is always the option of using neural networks (NNs) [29]- [32], which are capable of keeping the performance of a beamformer at sufficient levels, while providing an instant response.…”

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confidence: 99%

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An Effective Modification of Conventional Beamforming Methods Suitable for Realistic Linear Antenna Arrays

Zaharis

Gravas

Lazaridis

et al. 2020

IEEE Trans. Antennas Propagat.

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Antenna array beamforming (BF) refers to a real-time procedure that aims at calculating the proper feeding weights applied to the array elements in order to create a main lobe and a number of nulls toward respective preassigned directions. Most of the research performed on BF has been based on a simplified mathematical model, which ignores the nonisotropic radiation pattern of the array elements and the element mutual coupling. This article introduces an innovative way to incorporate the actual radiation pattern of the array elements and the element coupling into two popular deterministic BF methods, thus making these methods applicable to realistic antenna arrays. These two modified methods are applied in several scenarios, where a desired signal and several interference signals with various directions of arrival are received by a realistic microstrip linear antenna array. The statistical analysis performed in every scenario demonstrates the validity and effectiveness of the proposed modification. Index Terms-Antenna array beamforming (BF), direction of arrival (DoA), microstrip arrays, minimum variance distortionless response (MVDR), mutual coupling, null steering beamforming (NSB). I. INTRODUCTION A NTENNA array beamforming (BF) is related to a particular problem that has to be solved in real time. It concerns the calculation of feeding weights applied by a proper feeding network to the elements of the antenna array in order to make the array create a main lobe and a number of radiation nulls toward respective preassigned directions [1]-[19]. In fact, the main lobe direction must coincide with the direction of Manuscript

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“…The method is applied to unequally spaced linear arrays, takes into account the mutual coupling between the array elements and is implemented by using iterative FFTs via virtual active element pattern expansion. Finally, in [49], thinned fractal antenna arrays are used to achieve main lobe steering together with null control and SLL reduction. The SLL reduction and the control of a single null are concurrently achieved by applying a combination of ant colony optimization (which is a discrete evolutionary method) and a least mean squares algorithm.…”

Section: Prior Artmentioning

confidence: 99%

Adaptive Beamforming With Sidelobe Suppression by Placing Extra Radiation Pattern Nulls

Gravas

Zaharis

Yioultsis

et al. 2019

IEEE Trans. Antennas Propagat.

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A new iterative adaptive beamforming (ABF) algorithm based on conventional beamformers is proposed, in order not only to steer the main lobe towards a desired signal and place radiation pattern nulls towards respective interference signals, but also to achieve a desired side lobe level (SLL). Thus, the algorithm becomes less susceptible to unpredicted interference signals than conventional beamformers. In each iteration, the algorithm finds the direction of the peak of the greatest side lobe, which is considered as direction of arrival (DoA) of a hypothetical interference signal, and the conventional beamformer is then employed to find proper antenna array weights that produce an extra null towards this direction. The iterative procedure stops when the desired SLL is obtained. The algorithm is applied on three conventional beamformers and is tested for various signal DoA, while the direction deviation of the main lobe and the nulls is recorded, to evaluate the algorithm in terms of robustness. The proposed algorithm needs a few iterations to achieve the desired SLL, and thus is much faster than any evolutionary iterative method employed for side lobe suppression. Finally, unlike methods that employ neural networks, the proposed algorithm does not need any training to become functional.

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Design of thinned fractal antenna arrays for adaptive beam forming and sidelobe reduction

Cited by 24 publications

References 25 publications

Fractal antennas and arrays: a review and recent developments

Fractal antennas and arrays: a review and recent developments

An Effective Modification of Conventional Beamforming Methods Suitable for Realistic Linear Antenna Arrays

Adaptive Beamforming With Sidelobe Suppression by Placing Extra Radiation Pattern Nulls

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