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This paper presents microstrip patch antenna array inspired by split ring resonators (SRR) for 5.8 GHz applications. The proposed microstrip patch antenna array inspired by split ring resonators is designed using FR-4 material with dielectric constant of 4.4, 1.6-mm thick substrate and loss tangent of 0.02. The split ring resonator has been loaded into the designed microstrip antenna array. Unloaded antenna arrays have a gain of 5.41 dB at 5.8 GHz, However split ring resonator-loaded antenna arrays provide a gain of 7.28 dB at the same 5.8 GHz resonant frequency. This microstrip patch antenna array inspired by split ring resonators is simulated using 3DEM of Mentor graphics electromagnetic simulator. To verify the theoretical and simulated results, antenna measurements are being prepared. [ABSTRACT FROM AUTHOR]

The article presents a high gain metamaterial (MTM) integrated modified golden spiral antenna for THz (Terahertz) applications. The MTM unit cell is designed by two decagon SRRs (Split Ring Resonator). The proposed antenna has the dimensions of 100 x 100 μm² with MTM decagon rings on the ground. The MTM integrated antenna resonates at 2.80 THz, 3.15 THz, and 3.46 THz with impedance bandwidths of 2.77 THz-2:88 THz and 3.00-3.70 THz. [ABSTRACT FROM AUTHOR]

Light fidelity (LiFi) and wireless fidelity (WiFi) can be applied with the same network under the different constraints, which is suitable for COVID-19 surveillance in hospitals. The LiFi network is a high-capacity and security platform. A COVID-19 surveillance system using LiFi is proposed, which consists of two switching modes: communication and surveillance. Firstly, the communication targets are to accommodate the electromagnetic interference (EMI) immunity and high-capacity and security data transmission, where secondly the COVID-19 surveillance can be applied. In operation, the up and downlink system uses a metamaterial antenna embedded by Mach Zehnder interferometer (MZI). An antenna consists of silver bars embedded at the microring center with two-phase modulators at its sides. The entangled source namely a dark soliton is applied to form the transmission, where the information security based on quantum cryptography can be managed. By using the suitable parameters, the whispering gallery modes (WGMs) are generated and the up and downlink nodes are formed. The input information is multiplexed with time to form the multiplexed signals, where the big data transmission (40 Pbit s - 1 ) can be employed. By using the surveillance mode, the plasmonic antenna can be applied for temperature and electric force sensors, which can offer the disinfectant spray and temperature sensor for COVID-19 applications. The optimum plasma force sensitivity is 0.16 N kg−1 mW−1. The center frequencies of 191.48 THz and 199.41 THz are obtained for uplink and downlink antennas, respectively. The optimum temperature sensitivity is 0.05 rads−1 °C−1. In conclusion, the novelty of proposed work is that the integrated sensor circuits are employed for COVID-19 surveillance in the hospital. The fuzzy-based system is designed for critical patient monitoring alert using this surveillance and management inside the hospital for COVID-19 patients. [ABSTRACT FROM AUTHOR]

Metamaterial (MM) is an artificial constituent, which as a distinct properties i.e., negative permittivity and refractive-index, which doesn't subsists naturally in the environment. MM is widely used in the antenna application owing to their abundant advantages. Split Ring-Resonator configuration in MM antenna can enhance the performance of antenna. Therefore, the present study aims to develop an improved regression model, which evaluates the performance of MM antennas effectively. In that context, initially, the study performs, pre-processing by removing the unnecessary data and missing values. Then, the feature extraction is employed with Bi-LSTM, which extracts the efficient features. Followed by this, the training and testing split is performed as 80% training data and 20% of testing data. The modified regression model is constructed with empirical loss function and XG-Boost algorithms. By implementing the proposed model, the prediction phase is enhanced efficiently. The experimental evaluation of the proposed model is accomplished with Metamaterial antenna dataset (MM antenna dataset), which is openly available and the analysis is done in terms of error rate and accuracy. The proposed system attains 99.23% accuracy rate. [ABSTRACT FROM AUTHOR]

A miniaturized end-fire microstrip patch antenna with enhanced bandwidth and high-gain characteristics is presented. The design uniquely integrates complementary circular split-ring resonators (CCSRRs) in the rectangular radiation patch and an optimized grid of crossed slots in the ground plane, generating a double-negative metamaterial (DNG-MTM) response. This innovative combination significantly improves antenna performance in terms of gain, bandwidth, and size. The antenna achieves a wide operating bandwidth from 3 GHz to 8.4 GHz, delivering an exceptional 90% fractional bandwidth, substantially outperforming conventional designs. A strategically positioned rectangular slot beneath the feed line mitigates bandwidth limitations at higher frequencies, further enhancing impedance matching. The compact design (28 mm $\times 34$ mm, or $0.28\lambda $ g $\times 0.33\lambda $ g, where $\lambda $ g is the guided wavelength at the lower edge of the frequency band) achieves a peak gain of 6.9 dBi, representing a major size reduction and gain enhancement compared to existing counterparts. The proposed antenna’s novel DNG-MTM structure, compact size, and high performance make it an ideal solution for C-band radar and mobile wireless communication systems. Simulated and measured results demonstrate good agreement, validating the effectiveness of the design and its advantages over current technologies.

Future communication, 5G, medical, and IoT systems need compact, green, efficient wideband sensors, and antennas. Novel linear and dual-polarized antennas for 5G, 6G, medical devices, Internet of Things (IoT) systems, and healthcare monitoring sensors are presented in this paper. One of the major goals in the evaluation of medical, 5G, and smart wireless communication devices is the development of efficient, compact, low-cost antennas and sensors. Moreover, passive and active sensors may be self-powered by connecting an energy-harvesting unit to the antenna to collect electromagnetic radiation and charge the wearable sensor battery. Wearable sensors and antennas can be employed in smart grid applications that provide communication between neighbors, localized management, bidirectional power transfer, and effective demand response. A low-cost wearable antenna may be developed by etching the printed feed and matching the network on the same substrate in the printed antenna. Active modules may be placed on the same dielectric board. The antenna design parameters and a comparison between the computation and measured electrical performance of the antennas are presented in this paper. The electrical characteristics of the new compact antennas in the vicinity of the patient's body were simulated by using electromagnetic simulation techniques. Fractal and metamaterial efficient antennas and sensors were evaluated to maximize the electrical characteristics of smart communication and medical devices. The dual- and circularly polarized antennas developed in this paper are crucial to the evaluation of wideband and multiband compact 5G, 6G, and IoT advanced systems. The new efficient sensors and antennas maximize the system's dynamic range and electrical characteristics. The new efficient wearable antennas and sensors are compact, wideband, and low-cost. The operating resonant frequency of the metamaterial antennas with circular split-ring resonators (CSRRs) may be 5% to 9% lower than the resonant frequency of the sensor without CSRRs. The directivity and gain of the metamaterial fractal antennas with CSRRs may be up to 3 dB higher than the antennas without CSRRs. The directivity and gain of the metamaterial fractal passive sensors with CSRRs may be up to 8.5 dBi. This study presents new wideband active meta-fractal antennas and sensors. The bandwidth of the new sensors is around 9% to 20%. At 2.83 GHz, the receiving active sensor gain is 13.5 dB and drops to 8 dB at 3.2 GHz. The receiving module noise figure with TAV541 LNA is around 1dB. [ABSTRACT FROM AUTHOR]

This paper presents a multiband coplanar waveguide (CPW)-fed concentric circle shaped patch antenna for WLAN, LTE-A, 5G Wi-Fi, and X-band applications, which is loaded with metamaterial unit cell. The proposed patch antenna employs arc shaped patch and concentric circle shaped patch achieves ultra-wideband operation. The proposed two-layer antenna configuration consists of metamaterial super-substrate. The measured reflection co-efficient (S11) demonstrated three wideband operation ranging from 3.06 to 4.72 GHz (B.W of 42%), 4.94–-6.19 GHz (B.W of 22%) and 6.50–10.56 GHz (B.W of 47.5%). The metamaterial structure is obtained through the arrangement of the proposed unit cell in 5 × 5 order. The proposed metamaterial structure properties were examined for wave propagation through the material in two major axes directions (x and y-axis). For both axes, the metamaterial exhibits near Zero refractive index for wide range of frequency. The addition of this super-substrate provides significant gain enhancement by 181% when the maximum gain reaches 6.2 dBi at X-band frequency. Since the proposed antenna is more efficient, it might be used for X-band operations such as satellite communication, military, and medical monitoring. [ABSTRACT FROM AUTHOR]

In this study, a dual-tuned mode of liquid crystal (LC) material was proposed and adopted on reconfigurable metamaterial antennas to expand the fixed-frequency beam-steering range. The novel dual-tuned mode of the LC is composed of double LC layers combined with composite right/left-handed (CRLH) transmission line theory. Through a multi-separated metal layer, the double LC layers can be loaded with controllable bias voltage independently. Therefore, the LC material exhibits four extreme states, among which the permittivity of LC can be varied linearly. On the strength of the dual-tuned mode of LC, a CRLH unit cell is elaborately designed on three-layer substrates with balanced dispersion values under arbitrary LC state. Then five CRLH unit cells are cascaded to form an electronically controlled beam-steering CRLH metamaterial antenna on a downlink Ku satellite communication band with dual-tuned characteristics. The simulated results demonstrate that the metamaterial antenna features' continuous electronic beam-steering capacity from broadside to −35° at 14.4 GHz. Furthermore, the beam-steering properties are implemented in a broad frequency band from 13.8 GHz to 17 GHz, with good impedance matching. The proposed dual-tuned mode can make the regulation of LC material more flexible and enlarge the beam-steering range simultaneously. [ABSTRACT FROM AUTHOR]

Metamaterial Antennas are a type of antenna that uses metamaterial to enhance performance. The bandwidth restriction associated with small antennas can be solved using metamaterial antennas. Machine learning is gaining popularity as a way to improve solutions in a range of fields. Machine learning approaches are currently a big part of current research, and they're likely to be huge in the future. The model utilized determines the accuracy of the prediction in large part. The goal of this paper is to develop an optimized ensemble model for forecasting the metamaterial antenna's bandwidth and gain. The basic models employed in the developed ensemble are Support Vector Regression (SVR), K-NearestRegression (KNR), Multi-Layer Perceptron (MLP), Decision Trees (DT), and Random Forest (RF). The percentages of contribution of these models in the ensemble model are weighted and optimized using the dipper throated optimization (DTO) algorithm. To choose the best features from the dataset, the binary (bDTO) algorithm is exploited. The proposed ensemble model is compared to the base models and results are recorded and analyzed statistically. In addition, two other ensembles are incorporated in the conducted experiments for comparison. These ensembles are average ensemble and K-nearest neighbors (KNN)-based ensemble. The comparison is performed in terms of eleven evaluation criteria. The evaluation results confirmed the superiority of the proposed model when compared with the basic models and the other ensemble models. [ABSTRACT FROM AUTHOR]

This study offers an adaptive dynamic sine cosine fitness grey wolf optimizer (ADSCFGWO) for optimizing the parameters of two types of antennas. The two types of antennas are metamaterial and double T-shape monopoles. The ADSCFGWO algorithm is based on an adaptive dynamic technique and two recently developed and powerful optimization techniques: a modified grey wolf optimization (GWO) based on fitness value and a sine cosine algorithm (SCA). The suggested approach utilizes both algorithms’ capabilities to better balance the exploration and exploitation responsibilities of the optimization process while achieving rapid convergence. First, a new feature selection approach is proposed to choose the most significant features from the metamaterial dataset using the suggested ADSCFGWO-based ensemble model for optimal performance. The ADSCFGWO algorithm also optimizes a bidirectional recurrent neural network (BRNN) to estimate the double T-shape monopole antenna characteristics. Several experiments were undertaken to demonstrate the superiority of the suggested algorithms by comparing their results to those of existing optimization algorithms, feature selectors, and regression models. In addition, a statistical analysis is offered to evaluate the algorithm’s effectiveness and stability. The findings demonstrate the suggested method’s efficacy and superiority over numerous competing algorithms.

Employing machine learning techniques in predicting the parameters of metamaterial antennas has a significant impact on the reduction of the time needed to design an antenna with optimal parameters using simulation tools. In this paper, we propose a new approach for predicting the bandwidth of metamaterial antenna using a novel ensemble model. The proposed ensemble model is composed of two levels of regression models. The first level consists of three strong models namely, random forest, support vector regression, and light gradient boosting machine. Whereas the second level is based on the ElasticNet regression model, which receives the prediction results fromthe models in the first level for refinement and producing the final optimal result. To achieve the best performance of these regression models, the advanced squirrel search optimization algorithm (ASSOA) is utilized to search for the optimal set of hyper-parameters of each model. Experimental results show that the proposed two-level ensemble model could achieve a robust prediction of the bandwidth of metamaterial antenna when compared with the recently published ensemble models based on the same publicly available benchmark dataset. The findings indicate that the proposed approach results in root mean square error (RMSE) of (0.013), mean absolute error (MAE) of (0.004), and mean bias error (MBE) of (0.0017). These results are superior to the other competing ensemble models and can predict the antenna bandwidth more accurately. [ABSTRACT FROM AUTHOR]

The design of an antenna requires a careful selection of its parameters to retain the desired performance. However, this task is time-consuming when the traditional approaches are employed, which represents a significant challenge. On the other hand, machine learning presents an effective solution to this challenge through a set of regression models that can robustly assist antenna designers to find out the best set of design parameters to achieve the intended performance. In this paper, we propose a novel approach for accurately predicting the bandwidth of metamaterial antenna. The proposed approach is based on employing the recently emerged guided whale optimization algorithm using adaptive particle swarm optimization to optimize the parameters of the long-short-term memory (LSTM) deep network. This optimized network is used to retrieve the metamaterial bandwidth given a set of features. In addition, the superiority of the proposed approach is examined in terms of a comparison with the traditional multilayer perceptron (ML), Knearest neighbors (K-NN), and the basic LSTM in terms of several evaluation criteria such as root mean square error (RMSE), mean absolute error (MAE), and mean bias error (MBE). Experimental results show that the proposed approach could achieve RMSE of (0.003018), MAE of (0.001871), and MBE of (0.000205). These values are better than those of the other competing models. [ABSTRACT FROM AUTHOR]

A phase error correction method is proposed to compensate for the phase error in super-resolution correlated imaging based on metamaterial antennas. The varying carrier frequencies of a metamaterial antenna can generate the random radiation field for super-resolution correlation imaging, but the variation of the signal carrier frequency leads to large phase errors in the imaging results. In this proposed method, the sampling matrix in the super-resolution correlated imaging algorithm is used to compensate for the phase errors. Each element of the matrix is multiplied by a compensation phase corresponding to the phase error, and the error is subtly removed from the algorithm. In the experiment, the antenna pattern at each frequency of the metamaterial antenna is measured and recorded. In addition, an external field experiment is also carried out, and the collected data are imaged with the improved algorithm. Experimental results show that this technology can effectively solve the effect of phase errors on imaging results caused by signal carrier frequency changes. [ABSTRACT FROM AUTHOR]

In this work, metamaterial (MTM) inspired a compact CPW-fed antenna with triple operating band is proposed. A rectangular Split Ring Resonator (SRR) is unified in a circular slot of the polygon-shaped radiator in MTM inspired antenna. The antenna exhibits three operating band which are based on metamaterial characteristics of unit cell. The CPW-fed antenna is ensuing 10 dB impedance bandwidth varies from 2.28 to 2.38 GHz, 3.07 to 3.78 GHz, and 5.05 to 7.03 GHz, whereas notch band exist from 2.39 to 3.06 GHz frequency. Metamaterial behaviour leads into the bandwidth enhancement as well as miniaturization in lower operating band with electric length of 0.14λ0 × 0.21λ0. The antenna archives the peak gain of 1.49 dB at 2.34 GHz, 2.04 dB at 3.32 GHz, and 4.14 dB at 6.5 GHz frequency. The measured results authenticate the simulated outcomes and consequently the proposed antenna can be pertinent in LTE, WLAN, and 5G communications. [ABSTRACT FROM AUTHOR]

The design of microstrip antennas is a complex and time-consuming process, especially the step of searching for the best design parameters. Meanwhile, the performance of microstrip antennas can be improved usingmetamaterial, which results in a new class of antennas called metamaterial antenna. Several parameters affect the radiation loss and quality factor of this class of antennas, such as the antenna size. Recently, the optimal values of the design parameters of metamaterial antennas can be predicted using machine learning, which presents a better alternative to simulation tools and trialand-error processes. However, the prediction accuracy depends heavily on the quality of the machine learning model. In this paper, and benefiting from the current advances in deep learning, we propose a deep network architecture to predict the bandwidth of metamaterial antenna. Experimental results show that the proposed deep network could accurately predict the optimal values of the antenna bandwidth with a tiny value of mean-square error (MSE). In addition, the proposed model is comparedwith current competing approaches that are based on support vector machines, multi-layer perceptron, K-nearest neighbors, and ensemble models. The results show that the proposed model is better than the other approaches and can predict antenna bandwidth more accurately. [ABSTRACT FROM AUTHOR]

In this work, a compact inset-fed microstrip patch antenna integrated with a double negative metamaterial superstrate is presented for terahertz applications. A rectangular-shaped inset-fed antenna is utilized as the main radiator, which gives an impedance bandwidth of 1.281–1.354 THz. To improve the bandwidth and gain characteristics, a nested rectangular ring-shaped metamaterial structure is designed. This structure shows double negative properties at the resonance frequency, which enhances the gain and bandwidth simultaneously. The designed antenna achieves a gain improvement of 1.9 dB at Φ = 0° and Φ = 90°. A reflection coefficient of −24 dB is achieved with a bandwidth enhancement of 26% at 1.32 THz. The antenna maintains very good radiation characteristics, and the peak gain value reaches 7.72 dB at 1.32 THz. This metamaterial-based antenna can be used for biomedical, imaging, and radar applications. [ABSTRACT FROM AUTHOR]

Metamaterial Antenna is a subclass of antennas that makes use of metamaterial to improve performance. Metamaterial antennas can overcome the bandwidth constraint associated with tiny antennas. Machine learning is receiving a lot of interest in optimizing solutions in a variety of areas. Machine learning methods are already a significant component of ongoing research and are anticipated to play a critical role in today’s technology. The accuracy of the forecast is mostly determined by the model used. The purpose of this article is to provide an optimal ensemble model for predicting the bandwidth and gain of the Metamaterial Antenna. Support Vector Machines (SVM), Random Forest, K-Neighbors Regressor, and Decision Tree Regressor were utilized as the basic models. The Adaptive Dynamic Polar Rose Guided Whale Optimization method, named AD-PRS-Guided WOA, was used to pick the optimal features from the datasets. The suggested model is compared to models based on five variables and to the average ensemble model. The findings indicate that the presented model using Random Forest results in a Root Mean Squared Error (RMSE) of (0.0102) for bandwidth and RMSE of (0.0891) for gain. This is superior to other models and can accurately predict antenna bandwidth and gain. [ABSTRACT FROM AUTHOR]

Metamaterial Antenna is a special class of antennas that uses metamaterial to enhance their performance. Antenna size affects the quality factor and the radiation loss of the antenna. Metamaterial antennas can overcome the limitation of bandwidth for small antennas. Machine learning (ML) model is recently applied to predict antenna parameters. ML can be used as an alternative approach to the trial-and-error process of finding proper parameters of the simulated antenna. The accuracy of the prediction depends mainly on the selected model. Ensemble models combine two or more base models to produce a better-enhanced model. In this paper, a weighted average ensemble model is proposed to predict the bandwidth of the Metamaterial Antenna. Two base models are used namely: Multilayer Perceptron (MLP) and Support Vector Machines (SVM). To calculate the weights for each model, an optimization algorithm is used to find the optimal weights of the ensemble. Dynamic Group-Based Cooperative Optimizer (DGCO) is employed to search for optimal weight for the base models. The proposed model is compared with three based models and the average ensemble model. The results show that the proposed model is better than other models and can predict antenna bandwidth efficiently. [ABSTRACT FROM AUTHOR]

In the vast spectrum of wireless communication, millimeter-wave (mmWave) technology emerges as a game-changer, promising to revolutionize connectivity and enable a myriad of applications across diverse industries. Operating in the frequency range between 30 GHz and 300 GHz, mmWave offers immense bandwidth and high-speed data transmission, making it ideal for applications that demand high capacity and low latency. In this comprehensive exploration, we delve into the multifaceted applications of mmWave technology, its impact on various sectors, and the transformative innovations it heralds. [ABSTRACT FROM AUTHOR]

In recent, years, compared with the traditional phased array, the new metamaterial antenna has many advantages. However, the normal operation of the metamaterial antenna must be assisted by the frequency conversion signal, and the current super-resolution imaging algorithm does not compensate the error caused by the frequency variation, resulting in the serious decline of the imaging quality or even the inability of imaging. In addition, the frequency variation and different distances in the echo signal are coupled with each other, so the error phase can not be compensated directly. Therefore, an improved method of super-resolution correlation imaging algorithm based on compressed sensing is proposed. The super-resolution correlation imaging algorithm based on compressed sensing is combined with metamaterial antenna to realize microwave correlation imaging with low system complexity, low cost and high resolution. The correctness of the proposed method is verified by design simulation experiments, and it is verified that this method can process both two- dimensional and three-dimensional imaging. [ABSTRACT FROM AUTHOR]

In this article, a metamaterial loaded high gain nine antennas based microwave breast imaging system has presented to detect an unwanted tumour in the breast phantom. The proposed antenna is designed on a modified version of a basic Vivaldi antenna. Single negative metamaterial structure has been loaded to the modified version Vivaldi to enhance far-field antenna properties like gain and radiation pattern, which is essential for the breast imaging system. The proposed antennas have achieved -10dB impedance bandwidth of 8.45 GHz (2.0- 10.45 GHz) and 7.9 dBi maximum gain in the operating band. To verify the time-domain performance, the fidelity factor is also calculated for the face-to-face orientation, which is near about 92.89%. After optimisation in high load phantom, near field directivity (NFD) is also analysed with the workload to ensure that the near field radiation properties. Finally, the nine metamaterial (MTM) antennas arrays are placed around the breast phantom in a hemispherical order to take the data of scattering parameters for tumour object analysis in a CST simulation environment. The extracted data has been processed through an imaging algorithm to reconstruct the image for identifying the unwanted tumour object inside the breast phantom.

In this study, a dual-tuned mode of liquid crystal (LC) material was proposed and adopted on reconfigurable metamaterial antennas to expand the fixed-frequency beam-steering range. The novel dual-tuned mode of the LC is composed of double LC layers combined with composite right/left-handed (CRLH) transmission line theory. Through a multi-separated metal layer, the double LC layers can be loaded with controllable bias voltage independently. Therefore, the LC material exhibits four extreme states, among which the permittivity of LC can be varied linearly. On the strength of the dual-tuned mode of LC, a CRLH unit cell is elaborately designed on three-layer substrates with balanced dispersion values under arbitrary LC state. Then five CRLH unit cells are cascaded to form an electronically controlled beam-steering CRLH metamaterial antenna on a downlink Ku satellite communication band with dual-tuned characteristics. The simulated results demonstrate that the metamaterial antenna features’ continuous electronic beam-steering capacity from broadside to −35° at 14.4 GHz. Furthermore, the beam-steering properties are implemented in a broad frequency band from 13.8 GHz to 17 GHz, with good impedance matching. The proposed dual-tuned mode can make the regulation of LC material more flexible and enlarge the beam-steering range simultaneously.

This article develops a novel low-profile meta-surface-based tripolarized antenna with complementary patterns for fifth-generation (5G) application. A shared aperture metasurface-based structure is first proposed, which is carefully studied by equivalent circuit models and field distribution. Then, to realize multiple polarization operation, the TM10, antiphase TM20, and TM00 modes are used and excited by suitable feeding networks. For horizontal polarization, wideband response is realized by coupling and combining the TM10/TM20 dual modes. An inductance-loaded TM00 mode is displayed by loading the shorting vias on the metasurface, which is used to implement vertical polarization. Finally, a metasurface-based tripolarized antenna with a low profile of $0.04\lambda _{0}$ ($\lambda _{0}$ is the free space wavelength at 3.30 GHz) is fabricated. The overlapped 10-dB bandwidths for all excitations are from 3.26 to 3.84 GHz (16.3%) with isolation greater than 22 dB, which well covers the 5G-N78 band. The measured peak gain and radiation efficiency are larger than 10.3 dBi and −0.42 dB (90.8%), respectively. The results indicate that the proposed antenna with a low profile, a simple and low-cost configuration, multipolarization, good bandwidth, high radiation efficiency, and gain performance could be widely used in sub-6 GHz 5G communication systems. [ABSTRACT FROM AUTHOR]

A phase error correction method is proposed to compensate for the phase error in super-resolution correlated imaging based on metamaterial antennas. The varying carrier frequencies of a metamaterial antenna can generate the random radiation field for super-resolution correlation imaging, but the variation of the signal carrier frequency leads to large phase errors in the imaging results. In this proposed method, the sampling matrix in the super-resolution correlated imaging algorithm is used to compensate for the phase errors. Each element of the matrix is multiplied by a compensation phase corresponding to the phase error, and the error is subtly removed from the algorithm. In the experiment, the antenna pattern at each frequency of the metamaterial antenna is measured and recorded. In addition, an external field experiment is also carried out, and the collected data are imaged with the improved algorithm. Experimental results show that this technology can effectively solve the effect of phase errors on imaging results caused by signal carrier frequency changes.

This paper presents the performance improvement of a microstrip patch antenna (MPA) using a novel double‐layer concentric rings metaplate (DLCRM) for fifth‐generation (5G) millimeter wave (mmWave) applications. To improve the performance of the proposed antenna, a DLCRM is placed above the MPA having an air gap. The design procedure is explained using the different shapes of DLCRM, and the double negative (DNG) characteristic of metamaterial is verified. Moreover, the effects of the DLCRM on the MPA are validated by experimental results. The proposed antenna attains a high‐gain of 11.59 dBi and has an impedance bandwidth from 27.1 GHz to 29.56 GHz (8.68%) which is the potential 5G mmWave band. The measurement result shows that the bandwidth of the antenna is improved by 2.04%, and broadside gain is increased by 4.69 dBi compared to the MPA without a DLCRM. Thus, the antenna provides high gains with wide bandwidth that makes it a suitable candidate for 5G mmWave applications. [ABSTRACT FROM AUTHOR]

In this paper, two asymmetric co-planar waveguide (ACPW) fed circularly polarized (CP) zeroth-order resonance (ZOR) antennas (Antenna I and II) are presented using a composite right and left-handed transmission line (CRLH-TL) approach. By adding a stub on the left side of the ACPW ground and adjusting its length, circularly polarization property has been achieved in Antenna I. The simulated 3 dB axial ratio bandwidth (ARBW) of Antenna I is 1750 MHz (3.50–5.25 GHz). Next, the left side ground plane of Antenna I is further defected by etching a quarter wavelength slit to introduce a notch band (Antenna II). Antenna II has an extended 10 dB return loss bandwidth of 2200 MHz (3.28–5.48 GHz) with a band notch from 4.18–4.65 GHz that isolates the WiMAX and 5.2 GHz WLAN bands. ARBWs of 1080 and 870 MHz are achieved in the first and second band of Antenna II. The overlapping 3 dB ARBW and 10 dB return loss bandwidths of Antenna II in these two bands are 770 and 830 MHz, respectively. [ABSTRACT FROM AUTHOR]

A multiresonant split ring resonator (SRR) composed of two circular‐shaped meandered strips is presented. Resonances are first analyzed by means of eigenmodes computation and field mapping. It is shown that a resonance can emerge from a standing wave taking place in each slot produced by a meandered strip. A slot operates as a two‐wire transmission line section short‐circuited at one termination and loaded by an open‐circuit at the other end. Consecutively, a resonance occurs approximately when a quarter‐wavelength matches the length of the slot. A resonance frequency shift is observed, and it is related to a transverse magnetic coupling between a first antisymmetric mode and a second symmetric mode. Finally, multiple resonances in an SRR are experimentally evidenced by spectroscopy of the input impedance of an SRR resonator antenna. Experimental results are favorably compared with simulation. [ABSTRACT FROM AUTHOR]

A design of asymmetric coplanar strip-fed (ACS) CRLH antennas for multiband operation is presented in this paper. Two different possible termination of the antenna is discussed. Comparison between ACS short circuit and ACS open circuit termination confirm that the open circuit termination has extra resonance band. The antenna resonance frequencies were optimized for WIMAX/WLAN frequencies. The antennas have compact size of 13.5 × 26.5 mm2 thanks to the asymmetric configuration. The antenna has size reduction up to 50% as compared to the patch antennas which are operated as the same frequency bands. The antennas are tested experimentally to validate the agreement between simulated and measured data. [ABSTRACT FROM AUTHOR]

This article presents a type of miniaturized high-efficiency patch antennas for UHF radio frequency identification (RFID) reader applications based on the composite right-/left-handed (CRLH) negative order resonance. Miniaturization is achieved by using the first negative order resonance (−1st mode). These proposed CRLH resonators are realized by etching gap on the patch surface, which acts as a series left-handed (LH) capacitor as well as an effective radiator, and using metallic screws on the corner as steadying posts while also providing an LH inductor. Different from the traditional mushroom structures, these screws are placed on the two sides or corner of the unit cells allowing unobstructed current and field flowing inside the cavity. This enhances the quality factor and radiation efficiency. In addition, only metallic sheets, screws, and one thin substrate are used in the design, therefore dielectric loss is basically eliminated. Overall, these proposed antennas achieve a miniaturized size, as well as a high gain and radiation efficiency. The radiation characteristics of these RFID antennas are similar to the conventional patch antennas due to the −1st-order operation. Four antennas, including linearly polarized, circularly polarized (CP), frequency-tunable, and polarization/frequency-reconfigurable antennas, are carefully designed, investigated, and experimentally verified. Remarkable agreement has been observed between simulation and measurement. These antennas well cover 902–928 MHz UHF band. RF range tests are carried out for application verification. They demonstrate a compact size, low-cost, low-loss, and high efficiency with easy implementation. The CP antennas exhibit a good bandwidth and an excellent axial ratio in the whole upper semisphere. They have been selected for mass production, which illustrates a good engineering application example of CRLH metamaterial antennas. [ABSTRACT FROM AUTHOR]

In this paper, a multiple input multiple output antenna which operates at 5.8 GHz for wireless local area network applications is proposed. The proposed antenna is composed of two sets of four elements antenna array (2 × 2) on the top and a novel metamaterial structure on the ground plane. Here, the ground plane, which includes a lattice of 2 × 5 unit cells of metamaterial structure, is utilized in order to improve parameters of the antenna. Thanks to the proposed metamaterial structure, not only gain and bandwidth of antenna are enhanced, but also mutual coupling is reduced. The final design, with an overall size of 137 × 77 × 3.048 mm3, resulted in a | S 11| <−10 dB bandwidth of 1.78 GHz and a peak gain of 9.2 dBi. In addition, the isolation is higher than 18 dB although the close separation from edge to edge of the two antennas is only 2 mm and radiation efficiency of 73% at the operating frequency band. All is simulated based on CST Studio software and the simulated S-parameter results of the antenna are in good agreement with measurement results. [ABSTRACT FROM AUTHOR]

In this article, an open-ended metamaterial antenna structure is designed for WLAN application. The antenna comprises of an interdigital capacitor (IDC) and spiral inductor with a partial ground plane. The IDC (shunt element) act as a varying parameter to control the zeroth-order resonance (ZOR) frequency, whereas spiral inductor (series element) is used to form a first negative order resonance frequency at 2.29 GHz. The ZOR mode has been excited at 4.53 GHz by employing complimentary right/left handed transmission line model in the structure and the first positive order resonance (FPOR) frequency is obtained at 4.9 GHz. A rectangular shaped stub has been used to act as a virtual ground for IDC. The proposed antenna design has total foot-print size of 0.29λ0 × 0.27λ0 × 0.024λ0. The fractional bandwidth of 20.41% (4.36–5.35 GHz) is achieved due to the merging of ZOR and FPOR mode respectively. In addition, it also exhibits a measured peak gain of 2.12 dB and 2 dB with a radiation efficiency of 77.76% and 87.62% at ZOR and FPOR frequencies respectively. A prototype of the proposed antenna structure has been fabricated and simulation results are experimentally rectified. A good agreement between simulation and measured results are obtained. [ABSTRACT FROM AUTHOR]

In this paper, novel techniques are presented for gain enhancement of a wideband directional conformal antenna. Initially a wideband conformal antenna is proposed as a basic antenna which consists of an array of three fork shaped elements. To achieve the gain enhancement of the basic conformal antenna, three triangular shaped parasitic elements and an array of 3 × 6 number of low index metamaterial unit cells are integrated on both side of the substrate. The phase velocity in the metamaterial region is higher than the other region due to low refractive index as compared with other region. So, the proposed metamaterial can be considered as a beam focusing lens. As a result, the proposed antenna is more directive with narrow beamwidth and the half power beamwidth is reduced by 24° in the H-plane. The gain of the proposed conformal antenna which is integrated with parasitic elements and metamaterial unit cells is enhanced by 1.8 dBi compared to basic conformal antenna. The impedance bandwidth of the proposed conformal antenna achieves a bandwidth of 22.3% from 3.1 to 3.88 GHz which is suitable for WiMAX application. [ABSTRACT FROM AUTHOR]

A compact dual wideband metamaterial antenna designed for wearable application is presented in this communication. A metamaterial resonator structure that works as a radiator resonates in dual-band frequencies. The antenna is operated in the frequency spectra of IEEE 802.11 a and b/g/n WLAN, WiMAX 2.3 and 5.5 GHz and GSM 1800 MHz bands. The antenna has wide measured bandwidth from 1.6 to 2.56 GHz (46%) and 4.24 to 7 GHz (49.11%) with average measured gain of 1.6 dB in the lower band and 5 dB in the upper band. The structure of the antenna is examined analytically with different bending dimensions and human body effect. The antenna geometry is fabricated on a jeans material and also measured on different body locations to analyze its performance. The maximum patch dimension of the proposed design is 0.1 λ × 0.1 λ mm2 with respect to the lower band. Excellent agreement is found between the simulated and measured results. [ABSTRACT FROM AUTHOR]

A technique to reduce the size and enhance the operating bandwidth (BW) of planar Yagi antennas, while maintaining their unidirectional radiation characteristics, is proposed in this paper. In this technique, the reflector element is loaded with mu-negative (MNG) metamaterial unit cells to excite a mu-zero resonance (MZR), which is independent of the size of the antenna. Thus, the antenna can operate at lower frequencies without the need to increase its physical size. To implement the proposed idea, the reflector, which acts as the host transmission line, is positioned at a close distance to the driven element, which is typically a dipole antenna. To validate the proposed technique, two design concepts based on coplanar and broadside-coupled strip configurations are presented, and a wideband Yagi antenna is presented. The antenna achieves a wide operating BW of 70% (0.72-1.48 GHz) with a peak front-to-back ratio (FBR) of 14 dB and peak gain of 4.1 dBi with a compact size of 0.24λ× 0.24λ, where λ is the wavelength at the lowest operating frequency. The proposed antenna achieves a 45% wider operating BW compared to similar structures, while being miniaturized by more than 60% compared to available structures that have over 50% fractional BWs. [ABSTRACT FROM PUBLISHER]

A miniaturized dual-band metamaterial (MTM) antenna has been designed in this article. The designed coplanar waveguide fed antenna has composed of inner split-ring resonator and an outer open ring resonator with rectangular stub. The series parameter of the antenna is used to determine the zeroth order resonance frequency due to short-ended boundary condition. The whole size of proposed structure is 20 × 25.5 mm2. This MTM antenna exhibits dual-band operation at 3.17 GHz (3.1-3.22 GHz) and 5.39 GHz (5.27-5.47 GHz). The proposed MTM structure achieves measured peak gain of 0.71 and 1.89 dB at 3.17 and 5.39 GHz, respectively. The proposed antenna can be used for recent radio communication in form of S-band application and Wi-MAX. [ABSTRACT FROM AUTHOR]

In this work, a pentagonal ring CPW-fed zeroth order resonating (ZOR) antenna with gain enhancement is proposed. Gain enhancement is achieved by means of electromagnetic bandgap structures (EBG) loaded on patch. The proposed antenna is operated in series resonant mode, therefore resonance frequency is dominated by series parameters of the conventional CRLH transmission line. The antenna comprises of a circular patch which is imposed by interdigital capacitor and EBG structures. Meandered line inductor is connected between patch and pentagonal ground plane in order to ensureminiaturization using CRLH resonant approach. Measurement results shows that proposed antenna offers ZOR resonance at 2.7GHz with 4.81%, 10 dB fractional bandwidth. The antenna offers simulated gain of 1.63 dBi and 80.6% radiation efficiency at ZOR frequency. Surface current distribution shows that how these CRLH - TL components responsible for origination of ZOR mode. Proposed antenna exhibits excellent radiation patterns with cross polarization level of -53 dB in the boresight direction. [ABSTRACT FROM AUTHOR]