Metamaterial Superstrate Research Articles

Metamaterial inspired superstrate loaded miniaturized quad port MIMO antenna for 5G C-band applications

This paper proposes a new quad-port Multiple-Input-Multiple-Output antenna with a unique Maze structure Epsilon Negative (ENG) Metamaterial superstrate for 5G NR C-band applications. The suggested 2x2 MIMO antenna has four microstrip antennas with a C-shaped stub inside the slot arranged orthogonally on a FR4 substrate. The overall dimension of the proposed 2x2 MIMO antenna is 0.62λ0 x 0.62λ0 x 0.02λ0, where λ0 is the free space wavelength at 3.7 GHz. The proposed MIMO antenna has excellent impedance matching over a bandwidth of 32% (3.2 GHz–4.4 GHz). The proposed antenna incorporates a superstrate layer composed of modified maze-structured metamaterial elements with a unit cell size of 0.16λ0 x 0.16λ0 x 0.02λ0 on a single-layer FR4 substrate to enhance the antenna's gain, improve isolation properties, and achieve size reduction. By strategically placing the metamaterial superstrate, it reduces the mutual coupling between the antennas and enhances peak isolation of < −30 dB. In order to accomplish the goals of isolation and gain improvement, the metamaterial superstrate is positioned 10.5 mm (0.13λ0) above the MIMO components. Furthermore, it attains a 3.54 dB peak realized gain, which is enhanced by 162% across the frequency ranges, and the overall size of the MIMO antenna is reduced to approximately 17%. Adequate values for factors such as the diversity gain, envelope correlation coefficient, channel capacity loss, and total active reflection coefficient are also determined for the MIMO antenna performance. The design prototype of the proposed antenna is built and verified by measurements that reveal a strong correlation with the simulation's output.

Enhanced Quad-Port MIMO Antenna Isolation With Metamaterial Superstrate

Enhanced Quad-Port MIMO Antenna Isolation With Metamaterial Superstrate

A broadband metamaterial superstrate based MIMO antenna array for sub-6 GHz wireless applications

A circularly polarised Multi-Input Multi-Output (MIMO) array antenna integrated with the metamaterial superstrate is proposed and developed. The proposed antenna configuration includes a substrate and superstrate, featuring a 2x2 array MIMO setup on the substrate, and a metamaterial layer configuration setup on the superstrate. Although use of metamaterial superstrate enhances the antenna performance, an air gap between the substrate and superstrate is introduced to further enhance the performance. This proposed antenna configuration significantly broadened the impedance bandwidth to 24.3 % (2.9–3.7 GHz), a substantial improvement compared to the MIMO antenna alone, which achieved only 2.85 % (3.46–3.56 GHz). Furthermore, it substantially increased the axial ratio bandwidth to 17.7 % compared to only 0.86 % of MIMO itself. Additionally, the peak realized gain increased from 2.5 dBic to 11.5 dBic. Operating effectively within the 2.9–3.7 GHz frequency range, the proposed antenna achieves port isolation < -30 dB between its ports making it suitable for MIMO applications. The proposed antenna occupies a volume of 1.4 λ x 2.8 λ x 0.09 λ excluding the connectors.

A MIMO Antenna Using I-Shaped Metamaterial Superstrate with Improved Gain and Isolation for Multiband Wireless Systems

A MIMO Antenna Using I-Shaped Metamaterial Superstrate with Improved Gain and Isolation for Multiband Wireless Systems

Design and analysis of double-layer parasitic split-ring resonator based on O-shaped engraved microstrip based radiating structure for 5G, WiMAX, WLAN and LTE applications

A novel approach of frequency tunability to cover multiple wireless applications by using four PIN diodes as a switching element is presented. Five switching modes of PIN diodes are analyzed for frequency tunability. The parasitic metamaterial superstrate achieves performance improvement shown in the design. Numerical analysis of metamaterial rings and equivalent circuit models of the SRR and PIN diode are also presented. The structure is analyzed regarding reflection response (S11), Gain, VSWR, directivity and E-field for 2 GHz–6 GHz. Computational analysis is performed by the HFSS simulator and is compared with the fabricated structure (FR-4) for verification. Copper and liquid-based material are used for performance analysis of all the models, and comparative analysis is included. Liquid-based split ring resonator provides a maximum total gain of 5.564 dB, reflection response of −43.36 dB and tunability of 510 MHz. The proposed antenna is used in 5G, WLAN, WiMAX and LTE applications.

DNG Metamaterial-Based Superstrate for Performance Enhancement of Compact Size Wideband Patch Antenna

Recently, electromagnetic metamaterials are of great interest to researchers because of their unusual electromagnetic properties. The proposed work presents a metamaterial as a superstrate for enhancing the performance parameters of a conventional patch antenna. The metamaterial unit cell is examined using classical waveguide theory to confirm its metamaterial properties such as permittivity and permeability at the resonant frequency. The proposed meta-structure comprises of a 5 × 5 array of circular-shaped split ring resonators backed with wire strips and placed above an inset-fed rectangular patch antenna that resonates at 9.96 GHz. The metamaterial superstrate improves the gain, impedance bandwidth, and radiation efficiency by 2.4 dBi, 770 MHz, and 18.4%, respectively and simultaneously reduces reflection coefficient by 5 dB. Several benefits such as compact size, simpler structure, low profile, and low cost have been obtained from this design. EM simulation of the proposed composite structure has been carried out with the help of the HFSS EM simulator and measurement has been done for validation.

Highly Efficient and Multiband Metamaterial Microstrip-Based Radiating Structure Design Showing High Gain Performance for Wireless Communication Devices

High-speed wireless communication devices need antennas to operate at multiple frequencies with high gain. The need for such antennas is increasing day by day. The proposed metamaterial superstrate antenna gives a high gain and multiband performance, which is required in high-speed wireless communication devices. The designed antenna is also applicable for C- and X-band communication devices. The structure consists of a simple patch and multiple split-ring resonator metamaterials on the superstrate region. The performance optimization is achieved by adjusting the feed position, varying the height of the superstrate layer and changing the thickness of metamaterial rings. The proposed design is analyzed for 4 GHz to 12 GHz. The performance analysis regarding the reflection coefficient, directivity, gain and electric field is observed. FR4 is used as a dielectric material that makes the design low-cost. The proposed design represents a minimum reflection coefficient response of −49 dB, a bandwidth of 490 MHz, a maximum electric field of 1.29 × 104 v/m, good directivity and a broader radiation pattern. The comparison between the simulated and the measured results is incorporated in the manuscript. A comparison of the presented design with other articles is included to check the novelty of the design. The proposed method helps to target applications such as WiFi, Earth observation and microwave links.

A Microstrip Antenna Using I-Shaped Metamaterial Superstrate with Enhanced Gain for Multiband Wireless Systems

This paper presents the design of a rectangular microstrip patch antenna (MPA) using the I-shaped metamaterial (MTM) superstrate. A seven × seven array of the I-shaped MTM unit cell is used as the superstrate to enhance the antenna performance. The antenna is fed by a microstrip feeding technique and a 50 Ω coaxial connector. An in-phase electric field area is created on the top layer of the superstrate to improve the performance of the antenna. The proposed I-shaped MTM-based rectangular MPA produces three operating frequencies at 6.18 GHz, 9.65 GHz, and 11.45 GHz. The gain values of the proposed antenna at 6.18 GHz, 9.65 GHz and 11.45 GHz are 4.19 dBi, 2.4 dBi, and 5.68 dBi, respectively. The obtained bandwidth at frequencies 6.18 GHz, 9.65 GHz and 11.45 GHz are 240 MHz (3.88%), 850 MHz (8.8%), and 1010 MHz (8.82%), respectively. The design and simulation of the antenna are done using the Computer Simulation Technology (CST) studio suite and MATLAB. The proposed I-shaped MTM-based rectangular MPA is fabricated on a low-cost FR-4 substrate and measured using the Agilent 8719ET network analyzer. The proposed antenna has an overall dimension of 70 × 70 × 1.6 mm3. A significant improvement in the gain of the antenna up to 74.28% is achieved. The obtained results confirm that the proposed multiband antenna has a high gain, and enhancement in bandwidth and radiation efficiency. These properties make the proposed antenna suitable for the multiband wireless communications systems such as Wi-Fi devices, radar systems, short- and long-range tracking systems, etc.

Design and Fabrication of a Low-Cost, Multiband and High Gain Square Tooth-Enabled Metamaterial Superstrate Microstrip Patch Antenna.

The manuscript represents a novel square tooth-enabled superstrate metamaterial loaded microstrip patch antenna for the multiple frequency band operation. The proposed tooth-based metamaterial antenna provides better gain and directivity. Four antenna structures are numerically investigated for the different geometry of the patch and tooth. These proposed structures are simulated, fabricated, measured, and compared for the frequency range of 3 GHz to 9 GHz. The electrical equivalent model of the split-ring resonator is also analyzed in the manuscript. The comparative analysis of all of the proposed structures has been carried out, in terms of several bands, reflectance response, VSWR, gain and bandwidth. The results are compared with previously published works. The effects are simulated using a high-frequency structure simulator tool with the finite element method. The measured and fabricated results are compared for verification purposes. The proposed structure provides seven bands of operation and 8.57 dB of gain. It is observed that the proposed design offers the multiple frequency band operation with a good gain. The proposed tooth-based metamaterial antenna suits applications, such as the surveillance radar, satellite communication, weather monitoring and many other wireless devices.

Performance Enhancement of Patch Antenna Using RIS and Metamaterial Superstrate for Wireless Applications

Performance Enhancement of Patch Antenna Using RIS and Metamaterial Superstrate for Wireless Applications

Design and fabrication of flexible and frequency reconfigurable antenna loaded with copper, distilled water and seawater metamaterial superstrate for IoT applications

The manuscript represents a novel superstrate metamaterial loaded microstrip patch antenna to achieve multiband frequency reconfigurability. The performance is observed for the frequency band of 4 to 8 GHz. Metamaterial property is enabled by engraving triangular-shaped split-ring resonators in the substrate. Frequency tunability is achieved based on the switching mechanism of three PIN diodes. Different materials are loaded in the split ring resonators like copper, distilled water, and seawater for the performance observation in terms of reflectance response, Bandwidth, gain and tunability. The design provides the reflectance response of −43.38 dB, Bandwidth of 220 MHz, and frequency tunability of 100 MHz. The proposed design is also giving the highest gain of 8.3 dB. The structure is fabricated using FR-4 to reduce the overall cost of the antenna, and it is tested using a vector network analyzer and anechoic chamber. Simulated results and fabricated ones are compared for reliability. The proposed design, with its flexible and reconfigurable capability, can be applicable in IoT applications.

Machine learning assisted metamaterial-based reconfigurable antenna for low-cost portable electronic devices

Antenna design has evolved from bulkier to small portable designs but there is a need for smarter antenna design using machine learning algorithms that can meet today’s high growing demand for smart and fast devices. Here in this research, main focus is on developing smart antenna design using machine learning applicable in 5G mobile applications and portable Wi-Fi, Wi-MAX, and WLAN applications. Our design is based on the metamaterial concept where the patch is truncated and etched with a split ring resonator (SRR). The high gain requirement is met by adding metamaterial superstrates having thin wires (TW) and SRRs. The reconfigurability is achieved by adding three PIN diode switches. Multiple designs have been observed by adding superstrate layers ranging from one layer to four layers with interchanging TWs and SRRs. The TW metamaterial superstrate design with two layers is giving the best performance in gain, bandwidth, and the number of bands. The design is optimized by changing the path’s physical parameters. To shrink simulation time, Extra Tree Regression based machine learning model is used to learn the behavior of the antenna and predict the reflectance value for a wide range of frequencies. Experimental results prove that the use of the Extra Tree Regression based model for simulation of antenna design can cut the simulation time, resource requirements by 80%.

Design and Performance Analysis of MIMO Patch Antenna Using Superstrate for Minimization of Mutual Coupling

For 5G communications, An different types Antennas are plays major role to minimize mutual couplings and here MIMO is important technology which uses patch antenna’s. Where the existing design focuses only on frequency reconfiguration, but it does not take advantage of the entire frequency and power spectrum. Therefore, the honeycomb-shaped Metamaterial cells used in the suggested antenna design serve as a superstrate for micro-strip patch antennas with a extensive range of actual negative permittivity and permeability, as well as a refractive index feature. Also, to reduce mutual coupling in current printed and other antennas. A metamaterial superstrate-based micro-strip antenna with RF MEMS Varactor diode switching is proposed in this paper. Based on a micro-strip antenna, metamaterials in the shape of circular and hexagonal arrays are employed as the superstrate. Also, the superstrate layers serve as a random, providing strength to the entire structure while also improving other antenna metrics such as gain and bandwidth. The design outputs for several metamaterial superstrates in terms of reflection coefficient (S11), gain, and bandwidth are compared by adding varactor diode switches to the metamaterial superstrate, which also allows for frequency reconfiguration. As a result, the suggested antenna was designed to reduce mutual coupling and improve system performance in 5G technology, specifically in mm-wave applications. The obtained results for metamaterial superstrate designs demonstrate high bandwidth and gain behavior.

Velocity Estimation of Target in MIMO Radar Environment with Unknown Antenna Locations

A new algorithm is formulated for MIMO Radar system where positions of target along with that of the transmitter and receiver antennas are unknown. This algorithm considers a widely separated antenna MIMO setup and can be used when transmitters and receivers are either stationary or moving at a very low velocity. Here, the algorithm estimates the location of target with respect to the location of the first transmitter. The TDOA and AOA available for LOS path between the transmitters and receivers along with the reflection path from the target are utilized here. AOA is used only for initialization of antenna positions and target location. Furthermore, accurate estimation using Davidon-Fletcher-Powell (DFP) Algorithm is performed. The paper introduces a new algorithm to compute velocity of a target. Here, first the FDOA is estimated using a novel approach and then velocity is estimated from the FDOA obtained. The velocity estimator for FDOA given tracks CRLB and FDOA estimation tracks its corresponding CRLB upto -12dB. The algorithm uses target and antenna locations to estimate velocity that can be found out from the algorithm introduced in paper.

A super wideband MIMO antenna with metamaterial superstrate for gain enhancement at WLAN frequency band

A super wideband MIMO antenna with metamaterial superstrate for gain enhancement at WLAN frequency band

Performance analysis of double-face logarithmic spiral metamaterial superstrate for full enhancement of circularly polarized 5G spiral patch antenna investigated using characteristic mode analysis

AbstractIn this article, a novel double-face logarithmic spiral metamaterial (LSMTM) superstrate-inspired multiple-input multiple-output (MIMO) for fully enhanced circularly polarized (CP) antenna system is examined for 5G wireless communications. This novel double-face LSMTM superstrate acts as a planar concave-concave lens. Initially, the antenna is designed with a circular spiral patch to generate CP radiation in the frequency band of interest. Then, at a height of 6.5 mm (0.606 λo) above the MIMO antenna, which has a 0.8 mm (0.075 λo) edge-to-edge separation, the LSMTM superstrate is employed for isolation, gain, and bandwidth improvement. The proposed superstrate enhances the isolation, gain, and bandwidth of the antenna by about 32 dB, 3.47 dB, and 900 MHz, respectively. In contrast to the conventional technique of verifying operation with a simulated surface current distribution, characteristic mode analysis (CMA) is used to provide a better explanation of the proposed antenna's different modes and the creation of circular polarization. Additionally, the CMA supports the development of an effective technique that can predict whether or not the isolation can be further improved. The simulated results align with the measured results and are well adapted for 5G wireless communication devices.

Design and Analysis of Metamaterial-Based SWB-MIMO Antenna

The design and analysis of a four-port multi-input multi-output (MIMO) super wideband antenna (SWB) with a metamaterial superstrate are proposed. Initially, a single antenna is constructed with a hexagonal radiator loaded with dodecagon slots along with a slotted partial ground. An impedance bandwidth of 4.1–14.7 GHz is achieved by using symmetric coplanar waveguide feeding technique and three iterations of dodecagon slot-loaded radiating element. The design is extended to a 2 × 2 MIMO antenna with dimensions 50 × 50 × 1.6 mm3. The four symmetrical SWB antennas are placed orthogonally to each other at four corners of a square-shaped FR4 substrate. A metamaterial superstrate is used above the four-port antenna to increase the antenna’s performance characteristics. A 7 × 7 array of rectangular metamaterial unit cells acts as a building block for the metamaterial superstrate to improve impedance matching, enhance isolation between the elements, and boost the antenna’s gain. The metamaterial unit cells are made up of three rectangular rings that are put on top of a 1.6 mm thick FR4 substrate. With a mutual coupling of (>15 dB), the antenna achieved S11 < −10 dB for an impedance bandwidth of 11 GHz. The gain enhancement of up to 1.73 dB is obtained in C and X bands using metamaterial superstrate. The antenna characteristics mainly peak gain, return loss, bandwidth, and isolation are examined. The simulated results affirm a decent deal with experimental results.

5G Antenna Gain Enhancement Using a Novel Metasurface

This article presents a Sub-6 GHz microstrip patch antenna (MPA) with enhanced gain using metamaterial (MTM) superstrate. The source MPA operates at 4.8 GHz and has a peak gain of 5.3 dBi at the resonance frequency. A window-shaped unit cell is designed and investigated through the material wave propagation technique. The unit cell shows an Epsilon Near Zero (ENZ)-Mu Very Large (MVL) behavior around 4.8 GHz. The unit cell has a fourfold geometry which makes it a polarization independent metamaterial. A double layer antenna is designed by placing a 4 × 4 MTM slab as a superstrate above the MPA at a height of 0.208λ0; where λ0 is the free-space wavelength at the resonance frequency of the antenna. Impedance matching and gain of the source antenna is improved using the metamaterial. The simulation as well as measurement results show that novel antenna system has a peak gain of 7.68 dBi at 4.8 GHz and an impedance bandwidth of 0.22 GHz. The overall dimension of the antenna is 75 × 60 × 15 mm3. The proposed antenna operates in the Sub-6 GHz band and is suitable for 5G applications.

A New Design of 5G Planar Antenna based on metamaterials with a high gain using array antenna

In this paper, a symmetrical monolayer metamaterial superstrate is placed on a microstrip patch antenna resonant at 3.5 GHz. MTM metamaterial based CSRR Complementary Split Ring Resonators, constituting two rectangular rings is opposite splits on both ends, which are printed on Rogers RT 5880 type substrate with relative permittivity of 2.2, tangential loss of 0.0009, and a thickness of 0.508mm. This resonator is capable of exhibiting an ε-negative permittivity. Moving an MTM superstrate loaded with a 2 × 3 grating on a single radiating element, provides a gain increase from 4.66 dBi to 5.67 dBi was found at its operating frequency, and the radiation pattern was directional and stable over the entire frequency band. For a 4×1 antenna array loaded with MTM, the gain reaches about 9.84 dBi. the proposed antenna is suitable for 5G mobile applications.

Metamaterial-Integrated High-Gain Rectenna for RF Sensing and Energy Harvesting Applications.

This paper presents a metamaterial (MTM)-integrated high-gain rectenna for RF sensing and energy harvesting applications that operates at 2.45 GHz, an industry, science, medicine (ISM) band. The novel MTM superstrate approach with a three-layered integration method is firstly introduced for rectenna applications. The integrated rectenna consists of three layers, where the first layer is an MTM superstrate consisting of four-by-four MTM unit cell arrays, the second layer a patch antenna, and the third layer a rectifier circuit. By integrating the MTM superstrate on top of the patch antenna, the gain of the antenna is enhanced, owing to its beam focusing capability of the MTM superstrate. This induces the increase of the captured RF power at the rectifier input, resulting in high-output DC power and high entire end-to-end efficiency. A parametric analysis is performed in order to optimize the near-zero property of the MTM unit cell. In addition, the effects of the number of MTM unit cells on the performance of the integrated rectenna are studied. A prototype MTM-integrated rectenna, which is designed on an RO5880 substrate, is fabricated and characterized. The measured gain of the MTM-integrated rectenna is 11.87 dB. It shows a gain improvement of 6.12 dB compared to a counterpart patch antenna without an MTM superstrate and a maximum RF–DC conversion efficiency of 78.9% at an input RF power of 9 dBm. This results in the improvement of the RF–DC efficiency from 39.2% to 78.9% and the increase of the output DC power from 0.7 mW to 6.27 mW (a factor of 8.96 improvements). The demonstrated MTM-integrated rectenna has shown outstanding performance compared to other previously reported work. We emphasize that the demonstrated MTM-integrated rectenna has a low design complexity compared with other work, as the MTM superstrate layer is integrated on top of the simple patch antenna and rectifier circuit. In addition, the number of MTM units can be determined depending on applications. It is highly envisioned that the demonstrated MTM-integrated rectenna will provide new possibilities for practical energy harvesting applications with improved antenna gain and efficiency in various IoT environments.