Metamaterial Antenna Research Articles

Optimized Two-Level Ensemble Model for Predicting the Parameters of Metamaterial Antenna

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 from the 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.

Bandwidth Enhancement of Circular Ring Patch by Loading Single Split Complementary Split Ring Resonator

Metamaterials have gained a lot of interest in modern wireless devices due to their electromagnetic characteristics and it is employed to improve antenna parameters such as bandwidth, gain and efficiency. The study presents a novel strategy of single split non-uniform width Complementary Split Ring Resonator (CSRR) equipped Circular ring Microstrip Antenna (CRMA). The radiating element dimensions are seen to be 20 mm x 20 mm at the initial working frequency wherein the CSRR is incorporated on the ground plane of CRMA. The single split non-uniform width metamaterial (CSRR) structure displays -10 dB impedance bandwidth at 11.1 and 13.56 GHz which is beneficial for applications pertaining to X and Ku band. The total bandwidth of the said metamaterial antenna is 4 GHz (10.73-14.75). Optimization is undertaken with the help of commercially assessable simulation software tool Ansys HFSS 2019 version and practically measured using network analyzer. It is quite obvious from the experimentation that the results calculated get along well with the assumed outcomes.

Wearable Metamaterial Dual-Polarized High Isolation UWB MIMO Vivaldi Antenna for 5G and Satellite Communications.

A low-profile Multiple Input Multiple Output (MIMO) antenna showing dual polarization, low mutual coupling, and acceptable diversity gain is presented by this paper. The antenna introduces the requirements of fifth generation (5G) and the satellite communications. A horizontally (4.8–31 GHz) and vertically polarized (7.6–37 GHz) modified antipodal Vivaldi antennas are simulated, fabricated, and integrated, and then their characteristics are examined. An ultra-wideband (UWB) at working bandwidths of 3.7–3.85 GHz and 5–40 GHz are achieved. Low mutual coupling of less than −22 dB is achieved after loading the antenna with cross-curves, staircase meander line, and integration of the metamaterial elements. The antennas are designed on a denim textile substrate with = 1.4 and h = 0.5 mm. A conductive textile called ShieldIt is utilized as conductor with conductivity of 1.8 × 104. After optimizing the proposed UWB-MIMO antenna’s characteristics, it is increased to four elements positioned at the four corners of a denim textile substrate to be employed as a UWB-MIMO antenna for handset communications, 5G, Ka and Ku band, and satellite communications (X-band). The proposed eight port UWB-MIMO antenna has a maximum gain of 10.7 dBi, 98% radiation efficiency, less than 0.01 ECC, and acceptable diversity gain. Afterwards, the eight-ports antenna performance is examined on a simulated real voxel hand and chest. Then, it is evaluated and compared on physical hand and chest of body. Evidently, the simulated and measured results show good agreement between them. The proposed UWB-MIMO antenna offers a compact and flexible design, which is suitably wearable for 5G and satellite communications applications.

Dual-band ambient energy harvesting systems based on metamaterials for self-powered indoorwireless sensor nodes

AbstractIn this study, we present a comprehensive dual-band ambient radio-frequency (RF) energy harvesting system, consisting of rectenna and power management circuit, to harvest energy from 2.45 and 5.8 GHz Wi-Fi. The rectenna employs a metamaterial antenna based on a split-ring resonator, which possesses omni-directional radiation pattern at both frequencies and compact size (0.18λ × 0.25λ at 2.45 GHz). The dual-band rectifier yields the highest efficiency of 42% at 2.45 GHz and 1 dBm input power, 30% at 5.8 GHz and − 7 dBm input power. The maximum RF-DC efficiency for each band is 72% at − 5 dBm and 27% at − 2 dBm, respectively. The power management circuit, consisting of a storing capacitor and a boost converter, is integrated to produce a stable, sufficient output voltage. The energy harvesting system, with its comprehensiveness, is suitable for supplying low-power wireless sensor nodes for indoor applications.

A Review on the History and Current Literature of Metamaterials and Its Applications to Antennas & Radio Frequency Identification (RFID) Devices

Metamaterials are artificially engineered novel substances (or matter) that exhibit properties not found in nature. One of the earliest examples of a metamaterial structure is the split-ring resonator. This article is a current review of metamaterials, what it is, its classification, and its applications towards the field of antennas and radio frequency identification (RFID) devices. There are two major types of metamaterial antennas: leaky-wave antennas, and resonant antennas. Antennas can be made from composite right-left handed metamaterials, or antennas can be loaded with a metamaterial screen such as a shelled electrically small antenna (ESA) fed by coax. Metamaterial resonators can aid in reducing the antenna size, help improve the gain, improve the directivity, improve the return loss, and control the radiation pattern (by loading the antenna with a tunable unit). Recent advances in printing and fabricating technologies have allowed for use of metamaterial antennas in wearable gadgets and textiles; and can be used in conjunction with RFID devices and tags to advance and aid (emergency) equipment used by first responders.

Microstrip Antenna with High Gain and Strong Directivity Loaded with Cascaded Hexagonal Ring-Shaped Metamaterial.

A new cascaded hexagonal ring-shaped metamaterial element is designed, which is arranged periodically and placed on the top of a traditional microstrip antenna to optimize the performance of the traditional antenna. The simulation results show that the new metamaterial microstrip antenna works at near 10 GHz, the impedance bandwidth is extended by 0.25 GHz and the gain is increased by 113.6% compared with a traditional microstrip antenna. Cross-shaped slots are etched on the ground plate of the microstrip antenna to widen the impedance bandwidth. It is shown that the impedance bandwidths at the resonant frequencies of 10 GHz and 14 GHz are broadened by 0.06 GHz and 0.56 GHz, respectively, and the gain of the slot-etched antenna is 13.454 dB. After the metamaterial unit structure is optimized, a nested double-hexagon ring-shaped electromagnetic metamaterial unit structure is proposed. The metamaterial slot microstrip antenna operates in two frequency bands of 10 GHz and 14 GHz; the relative bandwidths are increased to 16.9% and 19.4% with two working bandwidths of 1.74 GHz and 4.98 GHz, respectively; and the gain and directivity are also improved compared with the traditional microstrip antenna. The metamaterial unit structure proposed in this paper is of certain reference value for the variety of metamaterial and the application of metamaterial in traditional microstrip antennas.

Miniaturized flexible metamaterial antenna of circularly polarized high gain‐bandwidth product for radio frequency energy harvesting

SummaryA discussion of using an ultrawide band (UWB) Hilbert‐shaped metamaterial (MTM) antenna structure for RF energy harvesting is exemplified in this article to conduct the use of organic substrates. Therefore, the proposed design is structured as a low profile rectangular MTM array in the context of wearable systems. The antenna is mounted on a prepared indium‐nickel oxide‐based polymerized Palm fiber (INP) substrate and backed with a ground plane of square electromagnetic band gap (EBG) defects. Fifteen samples of INP substrate are prepared for this study. Thus, the prepared INP substrates characterizations are tested using a T‐resonator transmission line technique printed on an FR4 substrate. In this technique, the measured scattering parameters are interpreted from two resonators with two different characteristics impedance to be employed for retrieving the relative permittivity (εr) and permeability (μr). This process is included to ensure the prepared substrate properties controllability for microwave devices manufacturing. After that, the proposed antenna is manufactured from silver nanoparticle (SNP) printout. The performance of the proposed antenna is tested numerically and experimentally. It is found that the proposed antenna shows an UWB response to start from 3 and up to 10 GHz that suits different applications including IoT, 5G, and WiMAX system networks. The measured gain spectrum shows four peaks at 3.5, 4.2, 5.4, and 6 GHz with gain values of 1.1, 2, 3.4, and 3.9 dBi, respectively. Finally, the conversion efficiency of RF harvesting is measured experimentally for the antenna in case of flat profile and bended structure at the frequency bands of interest to reveal insignificant changes.

Performance Enhancement of Reconfigurable Metamaterial Reflector Antenna by Decreasing the Absorption of the Reflected Beam

In this study, a new concept for a Ka-band 5G communication tunable reflector metasurface (MS) for beam steering at 28 GHz is proposed. Varactor diodes are used as the tunability component of each unit cell of this MS. Significant improvements in beam steering and bandwidth performance were achieved using this new concept referred to as the stripes configuration. Several different geometries of unit cells arranged in stripes were designed to achieve better performance in directionality, gain, sidelobe level (SLL), and bandwidth in the stripes configuration. Simulation results for a three-stripe MS with different unit cells in each stripe showed better performance in the phase dynamic range and reduced reflectance losses compared to a typical one-stripe MS. The simulation results showed a significant improvement of 3 dB, depending on the steering angle in reflectance gain, compared to a uniform MS (one stripe). Furthermore, a significant improvement of approximately 50% in the accuracy of the steering angle for different operating frequencies was demonstrated. Manufacturing considerations are discussed in this study.

Complementary split-ring resonator and strip-gap based metamaterial fractal antenna with miniature size and enhanced bandwidth for 5G applications

This paper proposes two different types of metamaterial (MTM) antennas for fifth-generation (5G) mid-band frequency operation. The radiating patch of the proposed antenna is based on the combined Minkowski-Sierpinski carpet fractal structure. On the ground plane, two different types of MTM structures: Complementary split-ring resonator (CSRR), and Strip-gap are etched to enhance the overall bandwidth and gain of the antenna. The introduction of these structures on the ground plane also leads to antenna miniaturization. Both the proposed MTM structure based antennas resonate at 3.5GHz. The overall size of the two fabricated prototypes is 28×29.5 mm2 / 28×28.5 mm2, which shows the compactness of the proposed design by 43% / 42% as compared to the conventional microstrip patch antenna (MPA). The measured bandwidth/gain achieved by the proposed combined Minkowski-Sierpinski carpet fractal antenna (CMSFA) having CSRR MTM and strip-gap etched on the ground plane are 370 MHz / 2.42dBi and 440 MHz / 3.75dBi, respectively.

Toward Real Time Monitoring of Wafer Temperature in Plasma Chamber Through Surface Acoustic Wave Resonator and Mu-Negative Metamaterial Antenna

Surface acoustic wave (SAW)-based temperature sensors and wireless sensing systems were developed for real-time monitoring of the wafer surface temperature in a plasma chamber. A one-port SAW resonator was used for the temperature sensor because of its unique capabilities of 3less (wireless, batteryless, and chipless (no embedded interface electronics)). Three SAW sensors with different resonant frequencies of 380, 445, 475MHz were employed to distinguish individual sensor from the whole sensor units and prevent electromagnetic (EM) interference caused by a plasma driving frequency of 15.6 MHz in the plasma reactor. The changes of the reflection peaks in the measurement system were compared in three different cases. When the SAW sensor was connected to the antenna, the reflection peak corresponding to SAW resonant frequency was clearly observed in the reflection profile. When heat was applied to the SAW sensor by shining an infrared heater, only the reflection peak corresponding to the SAW resonant frequency was largely downshifted while the background reflection profile remained the same. High sensitivity and linearity were observed from the three sensors. The sensitivity increased on the same wafer surface as the center frequency of the sensor increased. A negligible change in the sensor resonance peak was observed when a plasma radiation was continuously illuminated on the sensor surface, indicating that the fabricated sensor with a Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> passivation layer protects well against energetic X-ray and EM radiations. The sensor resonance peaks were not changed by a plasma driving frequency of 15.6 MHz that was applied between top and bottom plates.

Metamaterial‐based linear phased array antenna with improved wide‐angle scanning bandwidth by parasitic metal strips

Two metamaterial-based linear phased array antennas with improved wide-angle scanning bandwidth are designed in this study. Metamaterial antenna element consists of a metamaterial patch, periodic metal strips, distributed metal strips and slot coupling feeding structure. The bandwidth of the metamaterial antenna is improved by loading the periodic metal strips. Wide-angle scanning bandwidth of arrays is attributed to the distributed metal strips. For an E-plane array, the central element has a relative bandwidth of 30.0% (4.33-5.86 GHz) for Voltage standing wave ratio (VSWR) <2 and the main beam can scan up to ±70° with a gain fluctuation less than 3.3 dB. For an H-plane array, the central element has a relative bandwidth of 26.2% (4.41–5.74 GHz) for VSWR <2 and the main beam can scan up to ±70° with a gain fluctuation less than 2.5 dB. Two 7-element linear phased array antennas are fabricated to verify the scanning performance. The measured and simulation results are in good agreement. The proposed antennas can be promising candidates for C-band radar and satellite communication.

Through Wall Imaging Radar Antenna with a Focus on Opening New Research Avenues

This review paper is an effort to develop insight into the development in antennas for through wall imaging radar application. Review on literature on antennas for use in through wall imaging radar, fulfilling one or more requirements/specifications such as ultrawide bandwidth, stable and high gain, stable unidirectional radiation pattern, wide scanning angle, compactness ensuring portability and facilitating real-time efficient and simple imaging is presented. The review covers variants of Vivaldi, Bow tie, Horn, Spiral, Patch and Magneto-electric dipole antennas demonstrated as suitable antennas for the through wall imaging radar application. With an aim to open new research avenues for making better through wall imaging radar antenna, review on relevant compressive reflector antennas, surface integrated waveguide antennas, plasma antennas, metamaterial antennas and single frequency dynamically configurable meta-surface antennas are incorporated. The review paper brings out possibilities of designing an optimum through wall imaging radar antenna and prospects of future research on the antenna to improve radiation pattern and facilitate overall simple and efficient imaging by the through wall imaging radar.

BANDWIDTH ENHANCEMENT OF MICROSTRIP PATCH ANTENNA

This paper discusses bandwidth enhancement of microstrip patch antenna using metamaterial and defected ground structure. A patch antenna is designed and simulated for 2.45GHz. Substrate is used for this purpose is FR4 glass epoxy with dielectric constant of 4.4 thickness of 1.6mm.The shape used for conventional patch antenna is rectangular with inset feed. For metamaterial antenna circular split ring resonator are used. Metamaterial SRR and Defected Ground Structure is designed and simulated for 2.45GHz. After comparing both antennas bandwidth enhancement antenna is reported. High Frequency Structure Simulator is used for this purpose.

Miniaturized UHF Band Microstrip Antenna Designed with Spiral Metamaterial Inclusions

A miniaturized microstrip antenna is designed with spiral metamaterials for the UHF band applications. One numerical demonstration shows that a metamaterial antenna with patch size of 80mm×80mm resonates at 818MHz. The electrical patch length is only 0.221λ, much smaller than the 0.51λ for a traditional microstrip antenna. The small antenna is observed with a bandwidth of 2.9% and total efficiency 94.8%.

Millimeter-long metamaterial surface-emitting antenna in the silicon photonics platform.

Integrated optical antennas are key components for on-chip light detection and ranging technology (LIDAR). In order to achieve a highly collimated far field with reduced beam divergence, antenna lengths on the order of several millimeters are required. In the high-index contrast silicon photonics platform, achieving such long antennas typically demands weakly modulated gratings with lithographic minimum feature sizes below 10 nm. Here, we experimentally demonstrate a new, to the best of our knowledge, strategy to make long antennas in silicon waveguides using a metamaterial subwavelength grating (SWG) waveguide core loaded with a lateral periodic array of radiative elements. The mode field confinement is controlled by the SWG duty cycle, and the delocalized propagating mode overlaps with the periodic perturbations. With this arrangement, weak antenna radiation strength can be achieved while maintaining a minimum feature size as large as 80 nm. Using this strategy, we experimentally demonstrate a 2-millimeter-long, single-etched subwavelength-engineered optical antenna on a conventional 220 nm SOI platform, presenting a measured far-field beam divergence of 0.1° and a wavelength scanning sensitivity of 0.13°/nm.

A Design of Compact Meta-material CRLH Antenna for Wireless Applications

This article presents a compact design of a composite-right-left-handed (CRLH) antenna for wireless applications. The antenna is fed using a coplanar waveguide (CPW) feed structure. The CRLH-antenna is comprised of one CRLH unit cell. The CRLH unit cell has a series capacitance (interdigital capacitor) and a shunt inductor (stub meander inductor). The antenna achieves compactness with a small size of 16.5 mm × 26 mm × 1.6 mm, thanks to the CRLH features such as nonlinear phase. The proposed antenna achieves a size reduction of better than 50 % with respect to the microstrip patch antenna operated at the same frequency band. The operating frequency band of the proposed antenna is from 5.83GHz to 6.3 GHz for WLAN applications, dedicated short range communications (DSRC), and intelligent transportation systems (ITS). Also, the antenna fulfills a radiation performance of omnidirectional pattern. To confirm the antenna design performances, a prototype is fabricated, and the reflection coefficient and radiation patterns are measured. Furthermore, the measured results have a good match with the simulation results.

A Survey on Beam Steering Techniques in Printed Antennas

&lt;span&gt;Beam steering antennas is essential part of various WCN (Wireless Communication Networks) such as radar and satellite communication. The increasing demand of high data rate, high SNR (Signal to Noise Ratio) and high gain, therefore pattern reconfigurable antennas are required to improve such properties. &lt;/span&gt;&lt;span&gt;Beam steering is the technique of changing the main lobe direction of radiation. The constructive and distractive interference are used to steer the lobe in specific direction. Beam steering is necessary in various communications such as localization, satellite, tracking system and airborne application.&lt;/span&gt;&lt;span&gt; Beam steering antenna decreases interference and power consumption and also increases directivity and gain. Beam steering antenna transmit and receive signals in specific direction. &lt;/span&gt;&lt;span&gt;Beam steering antenna decreases interference and power consumption and also increases directivity and gain. The researchers are interested to find optimal beam steering solution for single and multi-point application. &lt;/span&gt;&lt;span&gt;In past various techniques are used to achieve beam reconfigurable antennas. This paper presents, beam steering principle and their theory, beam steering techniques such as; Mechanical Steering, Beamforming, Switching Pin Diodes, Reflector and array antenna (Reflectarray), Parasitic Steering, Phase Shifters, Switched Beam Antennas, Metamaterial Antennas, Traveling Wave Antennas, Retro-directive Antennas, Integrated Lens Antennas (ILAS), merits and demerits and comparison among various techniques.&lt;/span&gt;

Tunable high-gain and multiband microstrip antenna based on liquid/copper split-ring resonator superstrates for C/X band communication

We proposed a tunable, high-gain and multiband metamaterial microstrip antenna. The design structure is analysed using simulation results and measured results. The split-ring resonator superstrate and complementary split-ring resonator are used as metamaterial elements and loaded in microstrip patch antenna. The high gain is achieved by using the stacking of metamaterial superstrate above the microstrip patch antenna. We have presented the comparison of gain by loading split-ring resonator superstrate layers. The tunability is achieved by switching on and off p-i-n diodes. Three different combinations of six p-i-n diode switches are used for tuning the frequency spectrum. The improvement in bands is also achieved by different switching conditions. The liquid metamaterial superstrate shows a better response compared to the copper metamaterial superstrate. The results in terms of electric field are also presented. The design results are compared with previously published results. The proposed antenna with its tuning capacity and the high gain feature can be applied in wireless communication applications for C/X band communication.

Metamaterial mechanical antenna for very low frequency wireless communication

Metamaterial mechanical antenna for very low frequency wireless communication

Recent Development of Non-Contact Multi-Target Vital Sign Detection and Location Tracking Based on Metamaterial Leaky Wave Antennas.

Microwave radar sensors have been developed for non-contact monitoring of the health condition and location of targets, which will cause minimal discomfort and eliminate sanitation issues, especially in a pandemic situation. To this end, several radar sensor architectures and algorithms have been proposed to detect multiple targets at different locations. Traditionally, beamforming techniques incorporating phase shifters or mechanical rotors are utilized, which is relatively complex and costly. On the other hand, metamaterial (MTM) leaky wave antennas (LWAs) have a unique property of launching waves of different spectral components in different directions. This feature can be utilized to detect multiple targets at different locations to obtain their healthcare and location information accurately, without complex structure and high cost. To this end, this paper reviews the recent development of MTM LWA-based radar sensor architectures for vital sign detection and location tracking. The experimental results demonstrate the effectiveness of MTM vital sign radar compared with different radar sensor architectures.