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In this paper, we propose a microstrip antenna that incorporates a dual-polarization and bidirectional focusing metasurface (MS) for achieving high-gain transmission in circular polarization (CP) and reflection in linear polarization (LP) radiation, respectively. Initially, we design a MS that enables independent manipulation of the transmitted CP wave at a lower frequency of 8.2 GHz and the reflected LP wave at a higher frequency of 16.2 GHz, respectively. The unit-cell of the MS comprises a combination of an outer bilayered split-ring resonator, along with inner arc-shaped and disk resonators, all separated by a dielectric substrate. Subsequently, a coaxial-fed laminated microstrip antenna is designed that is capable of realizing CP radiation with a gain of approximately 4.9 dBic at 8.2 GHz and LP radiation at 16.2 GHz with a gain of 4.8 dBi, respectively. To improve the radiation performance, we construct a coaxial-fed laminated microstrip antenna integrated with a dual-polarization and bidirectional focusing MS. This configuration enables the antenna to achieve high-gain CP radiation in transmission at 8.2 GHz with a peak gain of 13.1 dBic and high-gain LP radiation in reflection with a peak gain of 14.6 dBi at 16.2 GHz, respectively. The relative bandwidth of the MS antenna is 6.79% (at 8.2 GHz) of the transmitted CP wave and 13.54% (at 16.2 GHz) of the reflective LP wave, respectively. To evaluate the practicality of our proposed design, we fabricated and measured a coaxial-fed laminated microstrip antenna, both with and without the MS. The results obtained from these measurements closely align with our simulations, thereby validating the effectiveness of our proposed dual-polarization and bidirectional MS antenna. This antenna provides a practical solution for achieving dual-polarization radiation and facilitating high-speed information transmission in communication systems. [ABSTRACT FROM AUTHOR] more...

A new microwave metamaterial microstrip line (meta-MSL) is studied by integrating planar mushroom metamaterial structures into a conventional MSL. The meta-MSL is featured with an enhanced effective refractive index than the conventional, extracted from numerical demonstrations using the S-parameter method. The extraordinarily increased refractive index is found to be associated with weak dispersion and low dissipation loss, making the meta-MSL particularly beneficial to compact a microwave Wilkinson power divider (WPD). One metamaterial WPD (meta-WPD) is built using new meta-MSLs. Full-wave numerical calculations reveal that the new meta-WPD has low insertion losses, low reflections, and high isolations between the output ports, working as a good substitute for the conventional WPD. However, the new meta-WPD is exceptional in its small size, which is particularly useful in mobile and wireless applications where compact microwave components are in critical demand. [ABSTRACT FROM AUTHOR] more...

This paper presents an innovative microstrip antenna of compact dimensions, constructed utilizing advanced meta-materials tailored specifically for Ultra-Wideband (UWB) applications. The antenna design features two distinct meta-material surfaces, each intricately fabricated with engraved pi-shaped slits on the radiating plane and cross-shaped slits on the ground plane. The distinctive left-handed behavior exhibited by this meta-material originates from the collaborative interplay of capacitive and inductive effects engendered by the radiating and ground planes. The proposed antenna structure assumes the form of 30.8 × 27.6 × 0.8 mm3 and interfaces seamlessly with a 50Ω feed line via an SMA connector. Its electrical resistance encompasses a range extending from 3.5 GHz to significantly beyond 14.5 GHz, characterized by pronounced emission along the reference axis and a focused radiation pattern, distinctly enhancing frequency-related attributes. The fundamental objective driving the design of this antenna lies in its potential to facilitate uninterrupted communication among vehicles, a crucial aspect in vehicular communication applications. This goal necessitates a broad frequency spectrum to establish seamless connectivity in vehicular contexts. A thorough analysis of the research techniques, findings, and consequences was also given, providing insights into the bright future of metamaterial-based antennas in vehicular communication. [ABSTRACT FROM AUTHOR] more...

In this letter, a new technique to the design of an ultra-wideband (UWB) monopole hexagonal antenna with triple band-rejected functions and to restrict the interferences with the exist bands is proposed, the design has the form of a hexagonal patch and a ground plane having rectangular shaped etched in the back side of the substrate to achieve the UWB behavior. The triple-band filter feature is generated by inserting a metamaterial (MTM) as a split ring resonator slots (SRRs) and a complementary split ring resonators (CSRRs) strip, thus no extra size is needed. The triple band-elimination is for 3.3-3.9 GHz centered at 3.5 GHz for 5G band, 4.99-5.4 GHz centered at 5.2 GHz for wireless local area network (WLAN) band, and 6.2-6.8 GHz centered at 6.5 GHz for IEEE INSAT/Supra-extended C-band. The antenna dimension has a compact size of 20×25×1.6 mm³. Current distribution on the antenna is used to analyze the effect of MTMs on the antenna operations. The simple structure and small size of the antenna makes it suitable for most of the wireless communication systems. [ABSTRACT FROM AUTHOR] more...

This paper proposes a circularly-polarized (CP) metasurface antenna with ultra-wideband radar cross section (RCS) reduction. Initially, the relationship between RCS reduction and phase difference with different reflection amplitudes is analyzed theoretically. Inspired by the shared-aperture principle, a high-frequency resistive layer is introduced into the antenna element to further fulfill ultra-wideband RCS reduction and low-profile requirements. Numerical simulations demonstrate that the inserted layer has no effect on the radiation performance of the antenna array. Then, the proposed element and its orthogonal unit are arranged in a checkerboard pattern for good CP radiation. In this configuration, the proposed metasurface array antenna has a maximum gain of 16.7 dBi with 72.1% aperture efficiency. The bandwidth of 5 dB RCS reduction with x- and y-polarized incidences is 7.10–17.95 GHz and 7.34–17.85 GHz, respectively. The proposed design is verified by the fabrication of prototype antennas and measurements. [ABSTRACT FROM AUTHOR] more...

Abstract In this paper, a reconfigurable transmitarray unit cell using liquid metal is presented. It consists of three conducting layers where the geometries of the resonators, on the different layers, differ and consist of an arrow shape together with rotated split rings. The arrow‐shaped conducting layer has the capability to convert the polarization of the incoming waves by 90°. The split ring resonators, on the upper and lower conducting layers, have the same dimensions but different orientations (horizontal and vertical polarization). Several fluidic channels are placed beneath/above the conducting layers. The transmission behaviour of the unit cell can be changed by altering the geometrical parameters which is achieved by injecting the liquid metal into the channels. More than 300° phase shift range with a maximum S21 of ∼ −1.5 dB at 3.3 GHz is obtained. It exhibits 3 dB of insertion loss over a bandwidth ranging from 3.2 to 3.43 GHz. It is the first time that a transmitarray unit cell, reconfigured employing liquid metal, provides a combination of low insertion loss and large phase shift range. The proposed prototype was fabricated and measured within an open‐ended waveguide and the measured results agree well with the simulations and verify the effectiveness of the design. The reconfigurable transmitarray unit cell can be used to design beam‐scanning arrays, as well as for applications in wireless communications. more...

Abstract This paper presents a compact metasurface antenna with reconfigurable radiation patterns designed for 5G mm‐wave applications. The antenna consists of a metasurface with 3 × 3 unit cells of modified patches, two coupling slots on the ground plane, and a reconfigurable feeding network. The method of characteristic mode analysis is initially employed to identify the modes of the metasurface layer which are responsible for steering the radiation pattern of the antenna at angles of 0° and ±30°. By analysing the surface currents of these modes, the locations of the coupling slots are determined, making it easier to excite and combine the desired modes and steer the main beam of the antenna in specific directions. The pattern reconfigurability is achieved by switching PIN diodes in the microstrip feed network to excite the appropriate coupling slots. The proposed metasurface antenna, with dimensions of 0.9λ0 × 0.9λ0 × 0.08λ0 (where λ0 is the free space wavelength at the centre frequency of 27 GHz), was fabricated and tested. The experimental results showed a wide bandwidth of 22.71% achieved by combining the resonance frequencies of the slots and metasurface layer. Furthermore, the antenna exhibits three distinct main beams at +30°, 0°, and −30° with a peak gain of 8.95 dB. more...

Abstract A circular polarised (CP) microstrip antenna loaded with sunflower‐shaped metasurface (SSM) to enhance the bandwidth using characteristic mode analysis is proposed in this communication. The SSM, divided into inner and outer parts by a ring, consists of equally spaced sectors of equal angles. In this design, the coupled corner‐truncated microstrip antenna with a slot in the centre is employed to obtain CP radiation by exciting two orthogonal modes, which have a 90° phase difference. Meanwhile, it demonstrates that the SSM structure significantly expands the operational bandwidth and exhibits a stable radiation pattern at high frequencies. Simulation and measurement results confirm that this SSM antenna achieves a wide operating bandwidth of 64.3% (4.5–8.76 GHz) and a 3‐dB axial ratio bandwidth of 30.6% (4.7–6.4 GHz), while maintaining a compact profile of 0.68 × 0.68 × 0 0.08 λ03. more...

A circular polarised (CP) microstrip antenna loaded with sunflower‐shaped metasurface (SSM) to enhance the bandwidth using characteristic mode analysis is proposed in this communication. The SSM, divided into inner and outer parts by a ring, consists of equally spaced sectors of equal angles. In this design, the coupled corner‐truncated microstrip antenna with a slot in the centre is employed to obtain CP radiation by exciting two orthogonal modes, which have a 90° phase difference. Meanwhile, it demonstrates that the SSM structure significantly expands the operational bandwidth and exhibits a stable radiation pattern at high frequencies. Simulation and measurement results confirm that this SSM antenna achieves a wide operating bandwidth of 64.3% (4.5–8.76 GHz) and a 3‐dB axial ratio bandwidth of 30.6% (4.7–6.4 GHz), while maintaining a compact profile of 0.68 × 0.68 × 0 0.08 λ03. [ABSTRACT FROM AUTHOR] more...

In this paper, a reconfigurable transmitarray unit cell using liquid metal is presented. It consists of three conducting layers where the geometries of the resonators, on the different layers, differ and consist of an arrow shape together with rotated split rings. The arrow‐shaped conducting layer has the capability to convert the polarization of the incoming waves by 90°. The split ring resonators, on the upper and lower conducting layers, have the same dimensions but different orientations (horizontal and vertical polarization). Several fluidic channels are placed beneath/above the conducting layers. The transmission behaviour of the unit cell can be changed by altering the geometrical parameters which is achieved by injecting the liquid metal into the channels. More than 300° phase shift range with a maximum S21 of ∼ −1.5 dB at 3.3 GHz is obtained. It exhibits 3 dB of insertion loss over a bandwidth ranging from 3.2 to 3.43 GHz. It is the first time that a transmitarray unit cell, reconfigured employing liquid metal, provides a combination of low insertion loss and large phase shift range. The proposed prototype was fabricated and measured within an open‐ended waveguide and the measured results agree well with the simulations and verify the effectiveness of the design. The reconfigurable transmitarray unit cell can be used to design beam‐scanning arrays, as well as for applications in wireless communications. [ABSTRACT FROM AUTHOR] more...

This paper presents a compact metasurface antenna with reconfigurable radiation patterns designed for 5G mm‐wave applications. The antenna consists of a metasurface with 3 × 3 unit cells of modified patches, two coupling slots on the ground plane, and a reconfigurable feeding network. The method of characteristic mode analysis is initially employed to identify the modes of the metasurface layer which are responsible for steering the radiation pattern of the antenna at angles of 0° and ±30°. By analysing the surface currents of these modes, the locations of the coupling slots are determined, making it easier to excite and combine the desired modes and steer the main beam of the antenna in specific directions. The pattern reconfigurability is achieved by switching PIN diodes in the microstrip feed network to excite the appropriate coupling slots. The proposed metasurface antenna, with dimensions of 0.9λ0 × 0.9λ0 × 0.08λ0 (where λ0 is the free space wavelength at the centre frequency of 27 GHz), was fabricated and tested. The experimental results showed a wide bandwidth of 22.71% achieved by combining the resonance frequencies of the slots and metasurface layer. Furthermore, the antenna exhibits three distinct main beams at +30°, 0°, and −30° with a peak gain of 8.95 dB. [ABSTRACT FROM AUTHOR] more...

The manuscript presents the design and development of a Microwave Hyperthermia (MHT) applicator integrated with an Electromagnetic (EM) lens. The purpose of the proposed MHT applicator is to provide non-invasive microwave hyperthermia treatment for skin cancer. The proposed MHT applicator comprises of an EM lens (133.75 × 133.75 mm3) placed ahead of a Hybrid Fractal Microstrip Patch Antenna (HFMA) (30 × 26 × 1.645 mm3), backed by a Meshedgrid-shaped Artificial magnetic Conductor (AMC) (48 × 48 × 3.27 mm3) reflector at an optimal distance of 16 mm The prototype of the HFMA is fabricated on a Rogers (RT5880) substrate and offers an impedance BW of 278 MHz, for a frequency from 2.316 to 2.594 GHz. To improve the front-to-back ratio (FBR) of the proposed HFMA, an EM lens that reduces the beam width and concentrated the energy in the desired direction is integrated with the AMC-backed HFMA. The final MHT applicator configuration provides a 3 dB beam width of 49.6° and a gain of 7.35 dBi at 2.45 GHz. The testing and validation of the proposed MHT applicator is carried out in a simulation environment using Computer Simulation Technology (CST) Multiphysics for thermal analysis to check the temperature rise in the phantom. An in-vitro sample of skin phantom with a tumor is prepared using chemicals mimicking skin properties is exposed to the EM radiations emitted by the proposed HT applicator excited using a RF signal generator and power amplifier. the temperature rise in the phantom is recorded using optical temperature measurement probe. A temperature rise in the cancer-affected area up to 44 °C (Effective Temperature Area (ETA) 36 × 20 mm2) is observed in the simulation environment for an exposure time of approx. 45 min and in the measurement environment after a span of 25 minuites. A reported Specific Absorption Rate (SAR) value of 10 W/Kg shows that the proposed MHT applicator is safe for human exposure, and also reduces hot spots by enhancing the focus with controlled temperature, thus making the proposed applicator safe for human exposure. [ABSTRACT FROM AUTHOR] more...

Microstrip patch antennas play an important role in wireless communications to improve speed. Some of their benefits are low cost, low profile, and easy to fabricate. Existing research on microstrip patch antennas examines difficulties such as limited diversity performance, low radiation characteristics, and low efficiency. To address these issues, metamaterials are used to enhance diversity. This study focuses on designing a dual-band microstrip patch antenna for 5G applications to meet user demands with high data rates and enhance communication speed. To improve isolation and gain, a hexagonal-shaped Split Ring Resonator (SRR) was added to the substrate of the antenna. The proposed antenna model operates at frequencies greater than 28 GHz. The antenna dimensions are 25×25×0.15 mm, designed on a polyamide substrate with a loss tangent tan δ of 0.004, dielectric constant εr of 4.3, and relative permeability of 1. The suggested model was evaluated using several performance parameters, such as reflection coefficient, axial ratio, Voltage Standing Wave Ratio (VSWR), gain, and radiation patterns. The proposed model has S-parameter values of -17.6192 dB and -20.3264 dB, and gain values of 7.1 dB and 7.3 dB at 28.900 and 33.7400 GHz, respectively. [ABSTRACT FROM AUTHOR] more...

As the physical size of a communication system for satellites or unmanned aerial vehicles demands to be reduced, a compact antenna with high directivity is proposed as a core element essential to the wireless device. Instead of using a horn or an array antenna, a unit planar antenna is combined with a surface-modulated lens to convert a low antenna gain to a high antenna gain. The lens is not a metal-patterned PCB but is dielectric, which is neither curved nor very wide. This palm-sized lens comprises pixels with different heights from the backside of PolyPhenylene Sulfide (PPS) as the dielectric base. The antenna gain from the unit antenna of 4.5 cm × 4.5 cm is enhanced by 10 dB with the help of a compact dielectric lens of 7.5 cm × 7.5 cm at 24.5 GHz as the frequency of interest. The antenna design is verified by far-field measurement as well as near-field observation, including sensing a metal object behind a blocking wall by using an RF test bench. Moreover, antenna performance is understood by making a comparison with conventional designs of antennas in terms of directivity and physical sizes. [ABSTRACT FROM AUTHOR] more...

In this paper, a metamaterial inspired meandered line loaded antenna with dual-band characteristics for wireless applications is presented. Initially, the antenna is loaded with a single meandered line structure and operates over a single band with a center frequency of 5.64 GHz and circularly polarized (CP) radiation. Further, it is loaded with two more similar meandered line structures inducing an extra band with a center frequency of 3.4 GHz and hence operating as a dual band antenna with an impedance bandwidth of 11.4% and 33.7%, respectively, exhibiting CP radiation in its second band. Moreover, the antenna is backed with a metasurface (MS) at the ground side with a separation of 18.4 mm to enhance the gain and radiation of the antenna. The antenna exhibits good radiation characteristics with peak gains of 7.66 dBi and 8.7 dBi in the first and second bands, respectively. The antenna is fabricated, and promising experimental results have been observed. [ABSTRACT FROM AUTHOR] more...

In response to the demand for broadband antennas in 5G mobile communications, this paper proposes a compact broadband multiple-input multiple-output (MIMO) antenna array. By chamfering a radiation patch and adding parasitic patches, the antenna is miniaturized while also expanding its bandwidth. The mutual coupling between the two antenna elements is reduced by loading a double-layer metamaterial decoupling structure above the elements which consists of an open resonating ring and a square ring. The antenna is simulated and measured using the three-dimensional electromagnetic simulation software HFSS and a vector network analyzer. The results show that the proposed antenna has a good radiation performance of S11 < -10 dB in the operating band of 12.11-13.99 GHz (relative bandwidth of 14.41%). Furthermore, the isolation of the proposed MIMO antenna array in the operating band is improved by more than -18.8 dB on loading the metameterial structure, indicating that the array antenna is suitable for use in the Ku-band. [ABSTRACT FROM AUTHOR] more...

We demonstrate the generation of highly directive circularly polarized beams by proposing a meta-lens to calibrate the near fields over the holographic surface. Such a design possesses the merits of ultra-low profile as a lens system on the basis of phase compensation of a specific radiating aperture rather than the conventional consideration of the lens focus, and the ratio between the overall height of the antenna architecture and diameter of radiating aperture is only 0.09. Especially, the proposed meta-lens integrated holographic surface also offers a satisfactory solution to improve the overall efficiency of holographic antennas, and the experimental results verify the proposed design with 27.6 dBic measured gain and 40.4 % aperture efficiency at 15 GHz. We expect the proposed strategy of integrating phase compensation lens closely over the holographic surface, pave the way for highly efficient meta-radiators with ultra-low profile. [ABSTRACT FROM AUTHOR] more...

This paper presents a novel miniaturized ultra-wideband metamaterial absorber with a thickness of 0.069 λ L thick, engineered to suppress electromagnetic radiation in high-frequency chip packaging. The absorber's bandwidth is enhanced through the incorporation of lumped resistors and patterned metal strips. Simulation results reveal an absorption efficiency exceeding 90% across the frequency range of 17.3–33.5 GHz, while maintaining polarization insensitivity and angular stability. The absorption mechanism is investigated using equivalent circuit theory and the S -parameter inversion method, which demonstrate consistent impedance matching and advantageous loss characteristics throughout the wide band. Relevant objects were meticulously prepared and tested, yielding a high correlation between the measured and simulated results. The proposed absorber, when integrated into package chips and patch antennas, significantly reduces the far-field electric field amplitude in both applications. Specifically, the packaged chip shows up to 19.7 dB of electromagnetic radiation suppression and the patch antenna structure achieves over 10 dB of radiation suppression in the 24.2 GHz–30.4 GHz range post-integration. These results affirm the absorber's efficacy in effectively reducing unwanted electromagnetic radiation in specified frequency bands within complex electromagnetic environments. The absorber's demonstrated effectiveness provides a promising approach to address the increasing issue of electromagnetic radiation in progressively miniaturized electronic devices. [ABSTRACT FROM AUTHOR] more...

In this article, a Vivaldi antenna with broad bandwidth and high gain is proposed. The proposed antenna consists of a coplanar Vivaldi antenna (CVA) configuration etched with two rhombus slots at both sides of the radiation arm to improve bandwidth and gain at the low frequencies as well as maintaining antenna miniaturization. A compact broadband metasurface is loaded in the dielectric region between the two exponentially tapered lines to improve radiation performance in a wide frequency range without increasing antenna size. The antenna has been fabricated and measured, obtaining 1.27-9.4 GHz bandwidth covering L/S/C/X and ultra-wideband (UWB) lower bands. The measured gain ranges from 3 dBi to 9.67 dBi. With a miniaturized size of 100×100×1 mm3, good directional radiation pattern and high gain in the whole working band, the proposed antenna is a good candidate for the applications in multi-band coverage systems. [ABSTRACT FROM AUTHOR] more...

The need for faster communication in today's world has led to the need for antennas with high bandwidth and gain. A novel THz MIMO antenna based on metamaterial is presented in this manuscript for high-speed communication applications with broad bandwidth and high gain. The THz MIMO metamaterial antenna is designed using a C-shaped metamaterial resonator. The metamaterial antenna is also compared with a simple square patch MIMO antenna design for different antenna parameters like gain, reflection, and transmission coefficients. The metamaterial MIMO antenna gives a higher bandwidth of around 1.95 THz, three operating bands and a maximum isolation of about 80 dB. The maximum gain of the metamaterial MIMO design is 20.4 dB. The metamaterial MIMO antenna is also optimized for its geometrical parameters like slot length, slot width, substrate thickness and ground layer thickness. The optimized value of slot length, slot width, substrate and ground layer thicknesses are obtained as 10 µm, 10 µm, 1.5 µm and 1 µm, respectively. The MIMO parameters like ECC, DG, MEG, CCL and TARC are analyzed. All these parameter values fall within the standard requirement for MIMO antennas. The designed metamaterial MIMO antenna can be a good pick for 6G/TWPAN communication devices. [ABSTRACT FROM AUTHOR] more...

In this paper, a ferrite-filled rectangular waveguide as a balanced composite right/left-handed (CRLH) transmission line is considered. Based on the surface current density of dominant mode, a centerline longitudinal slot on the broad wall of this ferrite-filled rectangular waveguide can be radiate to the free space as a leaky-wave antenna (LWA). This proposed LWA has the both capability of the fixed-bias frequency scanning and fixed-frequency bias scanning from negative to positive angles. However, the gain of the centerline slotted ferrite-filled rectangular waveguide antenna is not acceptable. By adding another slot and changing the position of slots on the broad wall, the gain is improved to more than 9 dB in frequency range of 6.59–6.69 GHz. [ABSTRACT FROM AUTHOR] more...

In this article, a fractal slotted metamaterial inspired multiband antenna for wireless communication applications is presented. The proposed structure incorporates the fractal formation of a radiating patch attached with metamaterial SRR cell and rectangular slotted partial ground plane to cover multiple wireless standards. The antenna is printed on FR4 epoxy substrate material having the thickness of 1.6 mm and relative permittivity of 4.4. The antenna has compactness in size as 37 × 22 × 1.6 mm³ and achieves five wireless communication modes, including S band (2.4 GHz; WLAN: IEEE 802.11g), S band (3.65 GHz; WiMAX: IEEE 802.16e), C band (5.0/5.8 GHz; WLAN: IEEE 802.11a/j), X-band (Satellite communication, radar, terrestrial broadband, space communication), 5G NR bands (n41: 2.496-2.690 GHz, n46: 5.15-5.925 GHz, n47: 5.855-5.925 GHz, n53: 2.483-2.495 GHz, n102: 5.925-6.425), and Lower Ku band (Molecular rational spectroscopy). The antenna also showcases consistent radiation characteristics, gain, and efficiency across resonant bands crucial for obtained resonant bands regarding multi-standard wireless applications. It attains an optimized peak gain of 4.38 dBi and a radiation efficiency of 86.23%. [ABSTRACT FROM AUTHOR] more...

This paper addresses the limited gain of conventional Antipodal Vivaldi Antenna (AVA) at higher frequencies. We propose a novel Metamaterial Lens Vivaldi Antenna (MLVA) design that overcomes this limitation by integrating an exponentially tapered antenna lens and a strategically placed Near Zero Refractive Index (NRZI) metamaterial lattice. The MLVA achieves exceptional wideband performance with a −3 dB gain bandwidth exceeding 148.6% from 3.7 to 25 GHz. The result demonstrates a peak realized gain of 11.8 dBi at 11.2 GHz, compared to 9.1 dBi conventional AVA, especially beyond 5 GHz. The compact MLVA design measures only 120 × 78 × 1.524 mm3 (1.48 × 0.96 × 0.0188λ03) λ0 where free‐space wavelength is the lowest frequency and is fabricated on RO4350 B substrate with a 50‐Ω SMA connector. Key features of the design include exponential flaring, and trapezoidal lens geometries chosen for their inherent ability to effectively collimate and direct the spherical wavefront. The incorporation of a dielectric lens and metasurface further enhances gain and Front‐to‐Back Ratio (FBR) by directing the majority of energy in the end‐fire direction. Experimental results validate the effectiveness of the proposed design, confirming simulation predictions. These outstanding characteristics make the MLVA a promising candidate for diverse wireless communication and radar applications demanding high data rates across a broad frequency range. Plain Language Summary: This paper introduces a new type of antenna called the Metamaterial Lens Vivaldi Antenna (MLVA), designed to perform better at high frequencies than conventional Antipodal Vivaldi Antenna (AVA). By incorporating a special lens and innovative materials, the MLVA achieves a wide range of frequencies from 3.7 to 25 GHz and a high gain of 11.8 dBi at 11.2 GHz. The compact design (measuring 120 × 78 × 1.524 mm3 or 1.48 × 0.96 × 0.0188λ03) has been validated through simulations and real‐world tests. These improvements make the MLVA ideal for high‐speed wireless communication and radar systems. Key Points: The Metamaterial Lens Vivaldi Antennas (MLVA) offer higher gain and broader bandwidth than conventional Antipodal Vivaldi AntennasThe design uses an exponentially tapered lens and NRZI metamaterial lattice to enhance high‐frequency performanceThe compact MLVA, validated by simulations and experiments, is ideal for high‐data‐rate wireless communication and radar applications [ABSTRACT FROM AUTHOR] more...

Emerging miniaturized optically pumped magnetometers (OPMs) are becoming one of the most desirable approaches for biomagnetic imaging, especially for OPM with elliptically polarized light, which promises single‐light optical pumping and detection with high sensitivity. However, conventional schemes of this kind require a set of bulk polarization optics and tedious adjustment procedures, which compromise the system's compactness and practicality. In this paper, a novel chip‐scale OPM scheme that leverages the monolithic elliptical meta‐polarizer is presented and experimentally demonstrated. The meta‐polarizer with a side length of 3 mm is laid out on a 2 × 2 cm2 glass wafer. It offers the capability to convert arbitrary incident polarization into the desired elliptical polarization and exhibits a tailorable elliptical dichroism (ED) of ≈0.77 at the wavelength of 795 nm. A 4 × 4 × 4 mm3 vapor cell containing 87Rb and N2 is combined with this elliptical meta‐polarizer to construct a miniaturized OPM. The sensitivity of this sensor reaches approximately 13 fT/Hz1/2 in a four‐layer magnetic shield with a dynamic range near zero magnetic field ≈ ±0.55 nT. By exploiting the advantages of planar integrated optics, reduced footprints and scalability are promised. And this work paves the way for the integration of emerging quantum sensors on a chip. [ABSTRACT FROM AUTHOR] more...

This paper presents innovations in green electronic and computing technologies. The importance and the status of the main subjects in green electronic and computing technologies are presented in this paper. In the last semicentennial, the planet suffered from rapid changes in climate. The planet is suffering from increasingly wild storms, hurricanes, typhoons, hard droughts, increases in seawater height, floods, seawater acidification, decreases in groundwater reserves, and increases in global temperatures. These climate changes may be irreversible if companies, organizations, governments, and individuals do not act daily and rapidly to save the planet. Unfortunately, the continuous growth in the number of computing devices, cellular devices, smartphones, and other smart devices over the last fifty years has resulted in a rapid increase in climate change. It is severely crucial to design energy-efficient "green" technologies and devices. Toxic waste from computing and cellular devices is rapidly filling up landfills and increasing air and water pollution. This electronic waste contains hazardous and toxic materials that pollute the environment and affect our health. Green computing and electronic engineering are employed to address this climate disaster. The development of green materials, green energy, waste, and recycling are the major objectives in innovation and research in green computing and electronics technologies. Energy-harvesting technologies can be used to produce and store green energy. Wearable active sensors and metamaterial antennas with circular split ring resonators (CSSRs) containing energy-harvesting units are presented in this paper. The measured bandwidth of the matched sensor is around 65% for VSWR, which is better than 3:1. The sensor gain is 14.1 dB at 2.62 GHz. A wideband 0.4 GHz to 6.4 GHz slot antenna with an RF energy-harvesting unit is presented in this paper. The Skyworks Schottky diode, SMS-7630, was used as the rectifier diode in the harvesting unit. If we transmit 20 dBm of RF power from a transmitting antenna that is located 0.2 m from the harvesting slot antenna at 2.4 GHz, the output voltage at the output port of the harvesting unit will be around 1 V. The power conversion efficiency of the metamaterial antenna dipole with metallic strips is around 75%. Wearable sensors with energy-harvesting units provide efficient, low-cost healthcare services that contribute to a green environment and minimize energy consumption. The measurement process and setups of wearable sensors are presented in this paper. [ABSTRACT FROM AUTHOR] more...

In this article, a metamaterial horn antenna based on transformation optics (TO) is presented to generate a focused orbital angular momentum (OAM) beam. By applying the coordinate transformation, a metamaterial insertion inside the horn is designed to concentrate the radiated OAM beam. The TO-based insertion is further realized by using split ring resonators (SRRs). The metamaterial antenna is fabricated and measured to verify the design. A 13o reduction in the main lobe angle is realized in measurement by SRRs. [ABSTRACT FROM AUTHOR] more...

A terahertz fractal antenna integrated with a metamaterial frequency selective surface (FSS) is designed for gain enhancement purposes. The designed antenna operates in various modes of operation to provide biconical and conical radiation patterns. A novel frequency-selective surface has been constructed and combined with a simple fractal antenna structure to reduce the back radiation from the radiator and improve its gain. Detailed simulation studies have been performed using high-performance 3D EM analysis software. The FSS is also studied using an equivalent electric circuit model approach to verify the operation of the designed radiator system. The prescribed FSS integrated fractal radiator operates over a wide range of terahertz frequency spectrum extending from 3.7 to 10 THz with a relative bandwidth of 91.97%. The design of the FSS structure integrated with a simple patch enhances the gain from 7.78 dBi to 9.28 dBi at 4.06 THz and from 8.71 dBi to 11.9 dBi at 7.27 THz. Additionally, the performance of the proposed FSS integrated fractal aerial has been optimized using machine learning (ML) based techniques. Various machine learning algorithms using XG Boost, Artificial Neural Network, and Random Forest are used to optimize the design parameters and to predict characteristic parameters of the proposed structure at the THz regime. Conventionally, the optimization process by traditional EM solvers like HFSS, CST, etc. requires more processing time in case of designing complex antenna structures. The implementation of a machine learning-based optimization method increases the speed and accuracy of the simulation optimization process and also achieves acceptable performance. [ABSTRACT FROM AUTHOR] more...

This paper introduces a wideband circular patch antenna designed with a frequency selective surface (FSS) for sub-6 GHz applications. The proposed antenna features a monopole circular-shaped patch with a partial ground plane, delivering an omnidirectional radiation pattern in the azimuth plane, resulting in relatively uniform gain in all directions. An FSS metamaterial enhances the antenna's gain and improves the broadside radiation pattern. The design incorporates three inner circular patches connected to the main patch. The FSS utilizes hybrid square/circle loop-based unit cells. The antenna and FSS are simulated using CST software and subsequently fabricated on an FR-4 substrate. The measured results demonstrate an impedance bandwidth of 1.6 GHz with a peak gain of 5.4 dB at 3.5 GHz. The omnidirectional radiation pattern is converted into a directional one by placing a reflector FSS as a bottom substrate layer. The overall structure size is compact, measuring (0.34λ0 × 0.27λ0 × 0.016λ0), where λ0 is the freespace wavelength corresponding to the lowest resonant frequency within the operational bandwidth. This design achieves significant antenna size reduction and is well-suited for future sub-6 GHz applications. [ABSTRACT FROM AUTHOR] more...

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] more...

The integration of machine learning (ML) regression models in predicting the parameters of metamaterial antennas significantly reduces the design time required for optimizing antenna performance compared to traditional simulation tools. Metamaterial antennas, known for overcoming the bandwidth constraints of small antennas, benefit greatly from these advanced predictive models. This study applies and evaluates four ML regression models — Extra Trees, Random Forest, XGBoost, and CatBoost — to predict key antenna parameters such as S11, gain, and bandwidth. Each model’s performance is assessed using metrics like Mean Absolute Error (MAE), Mean Squared Error (MSE), R-squared (R²), Mean Absolute Percentage Error (MAPE), and Root Mean Squared Error (RMSE) across different training and testing set configurations (30%, 50%, and 70%). The Extra Trees model achieves the best performance for predicting gain, with an R² of 0.9990, MAE of 0.0069, MSE of 0.0002, RMSE of 0.0145, and MAPE of 0.3106. Feature importance analysis reveals that specific features, such as pr and p0 for gain and Y a and Xa for bandwidth, are critical in the predictive models. These findings highlight the potential of ML methods to improve the efficiency and accuracy of metamaterial antenna design. [ABSTRACT FROM AUTHOR] more...

This paper presents the design and analysis of a metamaterial-based compact dual-band antenna for WBAN applications. The antenna is designed and fabricated on a 0.254 mm thick semi-flexible substrate, RT/Duroid® 5880, with a relative permittivity of 2.2 and a loss tangent of 0.0009. The total dimensions of the antenna are 0.26λo×0.19λo×0.002λo, where λo corresponds to the free space wavelength at 2.45 GHz. To enhance overall performance and isolate the antenna from adverse effects of the human body, it is backed by a 2×2 artificial magnetic conductor (AMC) plane. The total volume of the AMC integrated design is 0.55λo×0.55λo×0.002λo. The paper investigates the antenna's performance both with and without AMC integration, considering on- and off-body states, as well as various bending conditions in both E and H-planes. Results indicate that the AMC-integrated antenna gives improved measured gains of 6.61 dBi and 8.02 dBi, with bandwidths of 10.12% and 7.43% at 2.45 GHz and 5.80 GHz, respectively. Furthermore, the AMC integrated antenna reduces the specific absorption rate (SAR) to (>96%) and (>93%) at 2.45 GHz and 5.80 GHz, meeting FCC requirements for low SAR at both frequencies when placed in proximity to the human body. CST Microwave Studio (MWS) and Ansys High-Frequency Structure Simulation (HFSS), both full-wave simulation tools, are utilized to evaluate the antenna's performance and to characterize the AMC unit cell. The simulated and tested results are in mutual agreement. Due to its low profile, high gain, adequate bandwidth, low SAR values, and compact size, the AMC integrated antenna is considered suitable for WBAN applications. [ABSTRACT FROM AUTHOR] more...

This paper presents a novel metamaterial-based terahertz antenna designed to address the bandwidth requirements of future 6G wireless networks. By incorporating metamaterial etching in the ground plane, the antenna demonstrates the generation of new frequencies, significantly increasing bandwidth compared to conventional designs. Multiple terahertz antenna designs are formulated using varied metamaterial configurations, yielding disparate profiles of return loss and gain depending on the specific design types. For instance, the utilization of various metamaterial designs in microstrip patch antennas involves the incorporation of a singular unit cell. This deliberate modification enhances the generation of unique and optimized outcomes in terms of antenna performance. The utilization of a ring resonator, distinct from configurations involving singular cuts, dual cuts, and dual split rings, demonstrates the capability to manipulate and regulate the attributes of electromagnetic radiation, particularly within the terahertz and microwave frequency ranges.A singular cut antenna exhibited a return loss of - 32.6 dB and a gain of 5.16 dB. Upon transitioning to a dual cut configuration, an enhancement in performance was observed, with the return loss improving to - 49.91 dB and the gain increasing to 5.21 dB. However, when employing a dual split ring design, a substantial increase in return loss was noted, reaching − 57 dB. Although the gain of the dual split ring antenna surpassed that of the singular cut antenna, it fell short of the gain achieved by the dual cut configuration, measuring at 5.24 dB. The terahertz antenna is integrated into the ground plane, making use of metamaterial structures. The terahertz range (0.3 to 10 THz) offers advantages for communications, imaging, and detection due to its wider bandwidth compared to microwave wireless communications. The paper introduces an antenna design optimized for 6G applications, effectively mitigating the escalating need for enhanced frequency and expanded bandwidth requirements in communication systems. [ABSTRACT FROM AUTHOR] more...

In recent days, breast cancer is one of the most prevalent forms, and it necessitates timely identification to provide effective treatment. The present research proposed an innovative approach for detecting tumours in humanoid breast tissue with a metamaterial-persuaded THz patch antenna. THz antennas play a substantial part in various applications, including the medical domain. This paper presents the novel tree-slotted metamaterial (TSM) patch antenna, which resonates in the frequency band of 2.04 THz. The proposed structures are designed and simulated using the CST tool. Further, the breast phantom is modeled with the proposed patch antenna and the antenna characteristics are evaluated for different tumor sizes in the phantom. The proposed TSM antenna produces excellent results like − 62.35 dB return loss, 8.734 dBi gain and 1.0015 VSWR while detecting the 25 mm tumour size. Based on current THz spectrum research, this proposed antenna is employed to detect breast cancer cells as a primary cancer surveillance system. [ABSTRACT FROM AUTHOR] more...

A new decoupling element technology is used to create a tiny circular patch mutiple input multiple output (MIMO) antenna measuring 20 × 25 × 1.6 mm3. A simple split‐ring resonator (SRR) metamaterial design with adjustable inner ring inductance and capacitance allows MIMO antennas to operate across several frequency bands. Tunable‐split ring resonators (T‐SRRs) are small and improve antenna element isolation. The proposed MIMO system provides isolation larger than 20 dB from 5.93 to 12.63 GHz. It is useful for radar applications since it includes the C‐band upper link (5.925–6.425 GHz) and the X‐band (8–12 GHz). With good tuning and network structure decoupling, antennas can operate in dual bands with isolation levels below −15 dB. Over 85% radiation efficiency and 72% miniaturization were achieved in the proposed MIMO antenna. The antenna has good radiation and diversity performance, including an envelope correlation coefficient < 0.1 and a diversity gain of 9.98 dB. These qualities make it suitable for advanced technology. [ABSTRACT FROM AUTHOR] more...

This article is an attempt to design and develop a metamaterial-based microwave absorber with a low profile, broad incidence angle and compactness in the microwave frequency range. Further, equivalent circuit model of the proposed structure is discussed based on circuit theory. The unit cell focuses on achieving maximum absorption at C-, X-, and K-band. The dimensions of the proposed design are ultrathin and compact, having an overall size of 8 mm × 8 mm × 0.8 mm. The dimensions are optimized in such a fashion to achieve three different peaks at three various bands (C, X and K), thereby making the triple-band behaviour of the metamaterial absorber possible. The structure provides absorption of 98.26 % absorption at 7.76 GHz (C-band) while absorption of 96.74 % is achieved at 10.26 GHz (X-band) and 99.92 % absorption at 19.32 GHz (K-band) of microwave regime. The experimental verification of design conform that the measured results are found to be in close agreement to simulated ones. [ABSTRACT FROM AUTHOR] more...

A novel metamaterial-element based frequency selective surface (FSS) is proposed in this paper for multiband radome for airborne application, which exhibits angular stability and polarization independence up to incidence angle, 60°C. The proposed metasurface radome consists of a combination of different patch-type elements in two cascaded layers, forming an electrically thin design suitable for aerospace applications. It operates in the frequency bands, S- (3.3 GHz), C- (4.8 GHz), and X- (9.1 GHz) with high transmission efficiency and good isolation between bands (< -20 dB). An equivalent circuit model of the proposed design is derived and validated with the simulated (based on HFSS) and measured results. Further, a multilayered planar laminate is designed using the proposed metamaterial-element based FSS that exhibits transmission bandwidths, 220 MHz, 1 GHz, and 1.3 GHz corresponding to S-, C-, and Xbands, respectively, w.r.t-1 dB insertion loss. The structural analysis of multilayered radome wall configuration confirms its suitability for shared aperture antenna integrated to leading wing structure of aircraft. [ABSTRACT FROM AUTHOR] more...

A compact fork‐shaped MIMO antenna system with a 2 × 2 arrangement with four elements is presented. The MIMO elements are arranged orthogonally to achieve a small overall size of 36 × 28 mm2 and a wide bandwidth for 5G mm‐wave applications. MIMO elements are positioned 4 mm from each corner of the substrate to achieve compact size and minimize coupling. To improve the isolation of the proposed MIMO system, a metamaterial slab is inserted in the middle of the substrate and between radiating elements of the MIMO antenna system, which improves isolation by 10 dB within the whole operating band and achieves maximum isolation of 65 dB at 34.5 GHz. The proposed MIMO system operates in the Ka‐band frequency range of 22–50 GHz with isolation greater than 30 dB and efficiency above 80% across the entire frequency spectrum for 5G communication. Additionally, the performance parameters of MIMO are examined, including diversity gain (DG) and envelope correlation coefficient (ECC), and it is found that they meet the required standards of DG approximately equal to 10 and ECC < 0.05. The proposed MIMO system has been fabricated and tested. The measured results are consistent with the design of the simulated structure using the CST Microwave Studio (CSTMWS) simulator. [ABSTRACT FROM AUTHOR] more...

AbstractTo achieve multiple low-frequency topological interface modes (TIMs) while maintaining lightweight and load-bearing capacities in metamaterial beams, we propose novel topological beams equipped with double quasi-zero-stiffness (QZS) resonators. Following the introduction of the negative stiffness (NS) mechanism, we derived the dispersion relations of the topological beams with double QZS resonators using the transfer matrix method (TMM), and performed comparative and parametric analyses of stiffness ratio on folded Dirac cones (DCs) and locally resonant band gaps (LRBGs). Thanks to the NS mechanism and the double degrees of freedom (DOFs) in the QZS resonators, we can realize double low-frequency DCs (< 500 Hz) in metamaterial beams. It is notable that adjusting the stiffness of oblique springs can tune the resonators’ effective stiffness, implying that we can custom the frequency of DCs and LRBGs by adjusting the QZS resonator. By altering the distance between two QZS resonators, we obtain two topologically distinct unit cells. Transmission simulations confirm the presence of multiple low-frequency TIMs at the interface between these two domains. We also find that the effect of mass and geometric defects at various positions on TIMs is minimal. The proposed metamaterial beams could inspire innovative low-frequency vibration energy harvesters and lightweight topological devices. [ABSTRACT FROM AUTHOR] more...

Reconfigurable intelligent surface (RIS), equipped with a large number of small, low‐cost, and re‐configurable elements, is envisioned as a potential enabler for the upcoming 5G‐Advanced and 6G networks. Here, based on a flexibly tunable and readily programmable RIS, the capability of beamforming toward arbitrary desired directions and coverage enhancement are investigated and experimentally demonstrated. The theory of RIS‐based beamforming is introduced, the simulated beamforming radiation patterns are provided, and an over‐the‐air radiated testing platform is designed for characterizing RIS beamforming performance. The RIS beam steering radiation performance tests are conducted, and the radiation patterns for different directions are extracted and analyzed. In addition, the indoor field trials on the RIS performance evaluation of enhancing coverage are reported. The field trials for multiple RIS‐deployed scenarios, including RIS mirror placement, RIS non‐mirror placement, and non‐RIS assisted scenarios, are conducted, and the channel characteristics for those scenarios are extracted and modelled. Significant improvements in overcoming path loss and shadow fading in typical coverage holes can be observed. The proposed testing method and measurement results may provide some insights into the design and optimization of RIS‐aided wireless communications. [ABSTRACT FROM AUTHOR] more...

In this paper, a novel negative refractive index metamaterial (NIM) is developed and characterized. The proposed metamaterial exhibits negative effective permittivity (εeffe) and negative effective permeability (µeffe) at millimeter wave frequency of 28 GHz. This attractive feature is utilized to enhance the gain of a microstrip patch antenna (MPA). Two thin layers of 5 × 5 subwavelength unit cell array of NIM are placed above a single MPA to enhance the gain of the antenna. Each unit cell has an area of 3.4 × 3.4 mm2. A gain increase of 7.9 dBi has been observed when using the proposed NIM as a superstrate. Furthermore, the NIM array is placed over a 2 × 2 array of MPAs with four ports to demonstrate versatility of the metamaterial. The total size of the 2 × 2 antenna array system with N-MTM is about 61.1 × 34 × 16mm3 (5.71λ × 3.18λ × 1.5λ, where λ is the free-space wavelength at 28 GHz). The measurement result indicate that the maximum gain of the antenna array is 13.5dBi. A gain enhancement of 7.55 dB in E-Plane and 7.25 dB in H-Plane at the resonant frequency of 28 GHz is obtained. The proposed antenna structure is suitable for 5G millimeter wave communications, in particular, for possible implementation in future millimeter wave access points and cellular base stations. [ABSTRACT FROM AUTHOR] more...

A novel compact microwave metamaterial absorber structure with a wide bandwidth is proposed. The absorber structure is designed on an FR4 substrate with a 2.4 mm thickness. The metamaterial absorber unit cell design consists of a combination of W and S-shaped structures in which splits are incorporated to have the effect of a split ring resonator. The proposed unit cell structure is designed to have a wide absorption band, which includes the X and Ku frequency bands. The optimized dimension of the unit cell is 0.071 λ0 × 0.71 λ0 where λ0 is the wavelength of the center frequency of the absorption band. The WS-shaped structures are oriented to absorb TE and TM waves for a wide range of polarization angles. The simulation results of the unit cell have shown absorption above 95% from 10.48 to 13.28 GHz. In addition, the absorber has an efficiency above 92% for incidence angles from 0° to 60° for fixed polarization. The unit cell structure and array are fabricated, and measurements are performed. The simulation and measured results have shown good agreement. The proposed metamaterial can be used in defense and radar surveillance applications. [ABSTRACT FROM AUTHOR] more...

This research article presents the design and realization of a flexible semi-circular shaped ultra-wideband (UWB) printed antenna based on metamaterial superstrate for medical applications. In this article, at first, the design of a semi-circle structured UWB patch antenna is performed which provides an ultra-wide impedance bandwidth [2.83–13.57] GHz and a peak gain of 5.17 dBi. In order to ameliorate the radiation performance, an array pattern of 5 × 5 metamaterial (MTM) unit cells are generated and placed over the proposed antenna. Also, both the antenna and the superstrate layer are printed on a flexible teflon material. The proposed design has an overall compact size of 32.1 × 34 × 0.6 mm3. Using the superstrate MTM unit cell, the measured operating bandwidth ranges from 4.03 GHz to 14 GHz and the experimental peak gain and radiation efficiency are 6.7 dBi and 97.26%, respectively. Moreover, the conformal analysis is investigated to verify the robustness and the applicability of the prescribed antenna over the curved surfaces. The suggested antenna presents magnificent performance by maintaining ultra-wide bandwidth and offering required radiation characteristics during various bending analysis. Furthermore, the reflection coefficient and specific absorption rate (SAR) of the proposed antenna have been analyzed by placing it on different human body parts such as the hand, arm and chest. The suggested antenna maintains UWB characteristics along with acceptable SAR values for 1 g and 10 g tissues for various on body analysis cases. Hence, this UWB antenna structure can be a convenient choice for implementing on curved surfaces in flexible/bending conditions and also for wearable applications. The prescribed antenna could be useful for portable medical devices within the UWB spectrum. [ABSTRACT FROM AUTHOR] more...

In this paper, a spiral-shaped metamaterial-loaded rhombic slotted microstrip patch antenna is investigated for Sub-6 GHz 5G and 6 GHz tri-band applications. A 1.524 mm thick Rogers RO4003 substrate (ϵr = 3.55, LosTanδ = 0.0027) opts for the antenna design. A partially grounded mechanism is implemented to control the operating frequencies of the antenna. A 5×5 triangular unit cell metasurface is deposited beside the partial ground plane to enhance the impedance bandwidth as well as to improve the impedance matching. A G-shaped metallic structure enclosed within the rhombic slotted antenna helps in creating circular polarization (CP) properties. The presented antenna resonates at 3.28 GHz (Mid-range Sub 6 GHz 5G band), 4.94 GHz (Upper range Sub 6 GHz 5G band), and 6.92 GHz (Sub 6 GHz 6G Band) frequencies. The maximum gain offered by the antenna is 8.81 dBi. Also, the developed antenna offers CP characteristics in all three operating bands with wide axial ratio (AR) bandwidth characteristics above 400 MHz in both the first and third operating bands. The radial characteristics of the proposed antenna show its capability of receiving EM signals from all directions as desired for a WPT system. For validation purposes, a prototype is fabricated and characterized as well. [ABSTRACT FROM AUTHOR] more...

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] more...

A novel, compact, monopole apple-shaped, triple-band metamaterial-printed wearable antenna backed by a uniplanar compact electromagnetic bandgap (UC-EBG) structure is introduced in this paper for wearable wireless and medical body area network (WBAN/MBAN) applications. A tri-band UC-EBG structure has been utilized as a ground plane to minimize the impact of antenna radiation on the human body and improve antenna performance for the proposed wearable antenna. Metamaterial triangular complementary split ring resonators (TCSRRs) are incorporated into the antenna and UC-EBG structure, resulting in a compact UC-EBG-backed antenna with an overall size of 39 × 39 × 2.84 mm3 (0.41 λg × 0.41 λg × 0.029 λg). The printed textile antenna operates at 2.45 GHz for the wireless local area network (WLAN), 3.5 GHz for 5G new radio (NR), and 5.8 GHz for the industrial, scientific, and medical (ISM) bands with improved gain and high-efficiency values. Furthermore, the performance of the antenna is analyzed on the human body, where three models of curved body parts are considered: a child's arm (worst case) with a 40 mm radius, an adult's arm with a 60 mm radius, and an adult's leg with a 70 mm radius. The results demonstrate that the proposed antenna is an attractive candidate for wearable healthcare and fitness monitoring devices and other WBAN/MBAN applications due to its compact size, high performance, and low SAR values. [ABSTRACT FROM AUTHOR] more...

This study introduces a metasurface-based low-profile circularly polarized (CP) antenna with double-wide beam for global navigation satellite systems (GNSSs), which covers primarily BDS-2 B1 band and BDS-3 B1 band. At first, a T-slot structure achieving a compact design is presented to effectively miniaturize the antenna. Except that, a gear-type parasitic ring and eight parasitic microstrip lines are proposed to broaden both the half power beamwidth (HPBW) and axial ratio beamwidth (ARBW) of the antenna. Furthermore, a metasurface unit featuring double "WIFI" logo structure is introduced. This unit is expanded into a 7 * 7 metasurface loaded under the antenna, significantly improving its radiation characteristics. After experimentation, the proposed antenna achieves notable results: 121° HPBW and 214° 3 dB-ARBW at 1.561 GHz and 121° HPBW and 236° 3 dB-ARBW at 1.575 GHz. Additionally, it demonstrates more than 3.52 dBic gain across the whole frequency band, whose simulation and test results are in agreement. These results show that the antenna can be used for various satellite communication systems necessitating CP antennas with wide ARBW and HPBW. [ABSTRACT FROM AUTHOR] more...

Owing to their remarkable capability to modify electromagnetic waves at microwave and optical frequencies, metasurfaces are now the subject of a substantial amount of study and find utility in a wide variety of applications. These artificial sheet materials, which are typically made up of metallic patches or dielectric etchings in planar or multi-layer configurations with a thickness of subwavelength, have the benefits of being lightweight, easy to fabricate, and able to control wave propagation both on the surface and in the free space that surrounds it. This article provides an overview of recent advancements in the discipline and organizes those advancements according to their applications. The one-of-a-kind capabilities of many types of metasurfaces have come to light, beginning with the invention of frequency-selective surfaces, reconfigurable intelligent surfaces, and metamaterials. Patterning the metasurface unit cells allows for surface impedance to be altered and modified, which has wide-ranging applications in surface wave absorbers and surface waveguides. First and foremost, the purpose of this review article is to provide introductions to the fundamental metasurface, its important features, and application ideas. The authors address the most recent progress in metamaterial-inspired antennas and how they can be used to miniaturize antennas, increase gain and bandwidth, achieve circular polarization, and inhibit mutual coupling in multiple-input multiple-output (MIMO) antenna systems. In conclusion, exploring the research implications of the metasurface development trend and the significant engineering practical applications are shown in the conclusions. [ABSTRACT FROM AUTHOR] more...

A four elements MIMO (Multiple Input Multiple Output) antenna with improved isolation and compact size of 32 × 32 × 0.8 mm3 is proposed for C, X, Ku, K & Ka bands applications. This antenna also covering a band proposed for 6G communication (7–20 GHz). Initially, a ring-shaped elemental monopole patch antenna integrated with four perpendicular spaced spoke and staircase shaped DGS below fed line has been proposed. The elemental antenna shows a better reflection coefficient, good gain and directional radiation pattern at different frequency like X band (8–12 GHz), Ku band (12–18 GHz), K band (18–26.5 GHz) and Ka band (26.5–40 GHz) operating from 5.8 to 40 GHz with bandwidth of 34.2 GHz. To utilize the proposed antenna in multipath propagation environment MIMO configuration has been opted. Initially, a two-element based MIMO is investigated, finally the four element MIMO with a meshed metamaterial in ground to mitigate the problem of interferences among different elements of antenna has been done. Due to MIMO an improvement in bandwidth from 3.2–45 GHz is also observed covering C band (4–8 GHz). The proposed MIMO have an improved ECC, DG, TARC, Peak Gain and Group delay. Impedance circuit with passive elements is also observed using ADS software. [ABSTRACT FROM AUTHOR] more...

The electromagnetic compatibility analysis of RF circuitry is essential due to the adverse effects on sensitive components. Two metamaterial unit cells with slow‐wave properties are presented for cross‐talk reduction in transmission lines. The analytical expressions for computing equivalent lumped elements of the lines are then provided. The dispersion diagram is obtained from the parameters extracted from the measurement. A microstrip as the generator line and five identical CRLH unit cells as the receptor line are then used and a significant reduction in cross‐talk is observed in comparison to conventional lines. A non‐uniform transmission line with two different CRLH unit cells as the receptor line is then employed and found effective in further cross‐talk reduction between the lines. The lengths of the lines and numbers of cells are kept the same in all lines for comparison. The simulated results are validated by measurements. [ABSTRACT FROM AUTHOR] more...