Metamaterial-Inspired Antennas: A Review of the State of the Art and Future Design Challenges

Milias, Christos; Andersen, Rasmus B.; Lazaridis, Pavlos I.; Zaharis, Zaharias D.; Muhammad, Bilal; Kristensen, Jes T. B.; Mihovska, Albena; Hermansen, Dan D. S.

doi:10.1109/access.2021.3091479

Cited by 78 publications

(30 citation statements)

References 112 publications

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“…An antenna array is a collection of antennas used to achieve versatile functions, such as gain enhancement, beam steering, and multi-input-multi-output (MIMO) functionality [70]. Another way to manipulate electromagnetic waves in free space is by using metamaterials (MTMs), which are artificial structures with unnatural optical properties, such as negative permittivity and permeability [71]. Combining antennas and MTMs may result in many fantastic properties, such as miniaturization, gain enhancement, and high electromagnetic compatibility (EMC).…”

Section: Flexible Antennas and Arraysmentioning

confidence: 99%

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Flexible Liquid Crystal Polymer Technologies from Microwave to Terahertz Frequencies

Zhou

Qian

et al. 2022

Molecules

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With the emergence of fifth-generation (5G) cellular networks, millimeter-wave (mmW) and terahertz (THz) frequencies have attracted ever-growing interest for advanced wireless applications. The traditional printed circuit board materials have become uncompetitive at such high frequencies due to their high dielectric loss and large water absorption rates. As a promising high-frequency alternative, liquid crystal polymers (LCPs) have been widely investigated for use in circuit devices, chip integration, and module packaging over the last decade due to their low loss tangent up to 1.8 THz and good hermeticity. The previous review articles have summarized the chemical properties of LCP films, flexible LCP antennas, and LCP-based antenna-in-package and system-in-package technologies for 5G applications, although these articles did not discuss synthetic LCP technologies. In addition to wireless applications, the attractive mechanical, chemical, and thermal properties of LCP films enable interesting applications in micro-electro-mechanical systems (MEMS), biomedical electronics, and microfluidics, which have not been summarized to date. Here, a comprehensive review of flexible LCP technologies covering electric circuits, antennas, integration and packaging technologies, front-end modules, MEMS, biomedical devices, and microfluidics from microwave to THz frequencies is presented for the first time, which gives a broad introduction for those outside or just entering the field and provides perspective and breadth for those who are well established in the field.

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Section: Flexible Antennas and Arraysmentioning

confidence: 99%

“…Additionally, MTMs have been widely applied in LCP antennas [71]. SRRs have been designed on the antenna feeding lines to broaden bandwidth [95], and complementary SRRs have been used to obtain notch-band characteristics for UWB LCP antennas on the ground electrode [96,97].…”

Section: Metamaterialsmentioning

confidence: 99%

Flexible Liquid Crystal Polymer Technologies from Microwave to Terahertz Frequencies

Zhou

Qian

et al. 2022

Molecules

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“…where the refractive index is different throughout the lens rather than being dependent on the interfaces of the dielectric material to manipulate and shape the radiation beam. Among the most known lenses are Luneburg and Maxwell fisheye; the gradient refractive index distribution of the former is expressed by nr = √2 − (𝑟/𝘙) 2 , whereas the distribution of the latter is given by nr = n0 /1 + (r/R) 2 [125], [126]. In both formulas, R and r are the lens radius and the distance from any point to the lens centre, respectively.…”

Section: ) Grin Lens Based On Mtmmentioning

confidence: 99%

Overview of Planar Antenna Loading Metamaterials for Gain Performance Enhancement: The Two Decades of Progress

2022

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Metamaterials (MTMs) are artificially engineered materials with unique electromagnetic properties not occurring in natural materials. MTMs have gained considerable attention owing to their exotic electromagnetic characteristics such as negative permittivity and permeability, thereby a negative refraction index. These extraordinary properties enable many practical applications such as super-lenses, and cloaking technology, and are used to design different electromagnetic devices like filters, polarization converters, sensors, and absorbers. Advances in MTMs have made new application fields to emerge in communication subsystems, especially in the field of antennas. MTMs are usually arranged in front or above the radiating element, or incorporated in the same substrate to improve the performance of planar antennas, in terms of improving directivity, gain, bandwidth, and efficiency, reducing the size and mutual coupling, and deflecting the radiation characteristics. High gain antennas are demanded in modern wireless communication systems. Their importance is in improving the signal strength by reducing the interference and alleviating the free space path loss. This review paper provides a brief introduction to MTMs, with the focus on their operating principles. Furthermore, a detailed study of antenna gain enhancement based on the various properties of MTMs is carried out. MTMs with low values of constitutive parameters; zero-index material (ZIM), lowindex material (LIM), epsilon-near-zero (ENZ), and mu-near-zero (MNZ) are discussed in detail in the context of their capability to enhance the gain of a broad class of planar antennas. The low impedance property and lensing property, which is achieved by three different characteristics: high refractive index (HRI), gradient refractive index (GRIN), and negative refractive index (NRI) materials, are loaded to planar antennas for gain enhancement. The scope of this review has been limited to antennas that were experimentally validated in the respective source papers.INDEX TERMS Metamaterials (MTMs), gain enhancement, low impedance MTM, MTM lens, planar antennas, ZIM.

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“…Metamaterials(MM) are special materials that are not found in nature and are used in many fields with their unusual properties [1]. Metamaterials have a wide range of uses, including optical filters, medical devices, remote aerospace applications, sensor detection and infrastructure monitoring, smart solar power management, crowd control, high-frequency battlefield communication, and lenses for high-gain antennas, improving ultrasonic sensors, anti-radar devices, and superlenses.…”

Section: Introductionmentioning

confidence: 99%

Metamaterial Design with Nested-CNN and Prediction Improvement with Imputation

Kıymık

Erçelebi

2022

Applied Sciences

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Metamaterials, which are not found in nature, are used to increase the performance of antennas with their extraordinary electromagnetic properties. Since metamaterials provide unique advantages, performance improvements have been made with many optimization algorithms. Objective: The article aimed to develop a deep learning model that, unlike traditional optimization algorithms, takes the desired reflection coefficients’ parameter as an input and gives the image of the corresponding metamaterial. Method: An amount of 29,722 metamaterial images and reflection coefficients corresponding to the metamaterials were collected. Nested-CNN, designed for this task, consisted of Model-1 and Model-2. Model-1 was designed to generate the shape of metamaterial with a reflection coefficient as the input. Model-2 was designed to detect the reflection coefficient of a given image of metamaterial input. Created by using Model-2 in Model-1’s loss function, the nested-CNN was updated by comparing the reflection coefficient of the produced image with the desired reflection coefficient. Secondly, imputation, which is usually the complete missing data before the process of training in machine learning algorithms, was proposed to use in the prediction side to improve the performance of the nested-CNN. The imputation for prediction was used for the non-interested part of the reflection coefficient to decrease the error of the interested region of the reflection coefficient. In the experiment, 27,222 data were used for the KNN-imputer, half of the reflection coefficient was considered as the non-interested region. Additionally, 40 neighbors and 50 neighbors were given the best mean absolute errors (MAE) for specified conditions. Result: The given results are based on test data. For Model-2, the MAE was 0.27, the R2 score was 0.96, and the mean correlation coefficient was 0.93. The R2 score for the nested-CNN was 0.9., the MAE of nested-CNN was 0.42, and the MAE of nested-CNN with 50 neighbors was 0.17.

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Metamaterial-Inspired Antennas: A Review of the State of the Art and Future Design Challenges

Cited by 78 publications

References 112 publications

Flexible Liquid Crystal Polymer Technologies from Microwave to Terahertz Frequencies

Flexible Liquid Crystal Polymer Technologies from Microwave to Terahertz Frequencies

Overview of Planar Antenna Loading Metamaterials for Gain Performance Enhancement: The Two Decades of Progress

Metamaterial Design with Nested-CNN and Prediction Improvement with Imputation

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