Flexible Antenna Research Articles

Flexible and Compact Tri-Band Graphene Antenna for Conformal Wi-Fi/WiMAX/5G Applications

Flexible and Compact Tri-Band Graphene Antenna for Conformal Wi-Fi/WiMAX/5G Applications

A Design of Four-Port Flexible UWB-MIMO Antenna for Wearable and IoT Applications

A Design of Four-Port Flexible UWB-MIMO Antenna for Wearable and IoT Applications

Characteristics mode analysis based wideband Sub-6 GHz flexible MIMO antenna using a unique hybrid decoupling structure for wearable applications

This article presents a compact flexible four-element multiple input multiple output (MIMO) antenna for Sub-6 GHz wearable applications. A wideband monopole antenna with a modified edge tapered radiator and a lowered ground plane is replicated to form a four-element antenna. The proposed antenna is fabricated on a flexible polyethylene terephthalate (PET) substrate and holds an overall dimension of 65 × 56 × 0.25 mm3. The antenna has a measured bandwidth of 3.55–5.3 GHz with a peak gain of 4.9 dBi. A novel hybrid decoupling structure with a neutralization line in the radiator and a unique defective ground structure (DGS) suppresses the coupling current and provides isolation better than −24 dB throughout the bandwidth. The antenna design evolution is explained using characteristics mode analysis (CMA). The MIMO diversity performance is relatively good with MIMO diversity metrics showing envelope correlation coefficient (ECC) < 0.001, diversity gain > 9.99, total active reflection coefficient (TARC) < −10 dB, channel capacity loss (CCL) < 0.3 bps Hz−1 and multiplexing efficiency (ME) < −0.5. Specific absorption rate (SAR) analysis of the antenna is performed to check the antenna’s suitability in wearable applications and the proposed antenna exhibits 0.745 W kg−1 and 0.326W kg−1 for 1g and 10g of tissue respectively which is much less than the permissible international standards.

Effect of Ground on V-folding Flexible Kapton-based Antenna

Introduction: In this paper, we explore the world of flexible patch antennas, specifically focusing on their horizontal V-folding percentages. The folding of these antennas plays a crucial role in the realm of wireless communication. Methods: Our V-folding antenna is ingeniously crafted for seamless communication with objects featuring sharp curves. What sets our study apart is the exploration of the effects of Vfolding percentages on the current distribution, a novel approach. We closely monitored the surface current distribution of the V-folded antenna, considering the percentage-wise impact along with the influence of the ground plane. Delving deeper, we scrutinized changes in ground plane size and drew comparisons between a standard ground and a resized one in the context of the V-folded patch antenna. Results: The resized ground plane outshone its normal counterpart, exhibiting superior performance. With the normal ground, the FPA operated at 1.42 GHz and 4.485 GHz. Postresizing the ground, it showcased commendable stability in retaining the V-folding frequency shift. Conclusion: Crafting the antenna's structure was a meticulous process accomplished through the use of CST Microwave Studio software, and we validated our design using a vector network analyzer.

The coax monopole antenna: A flexible end-fed antenna for ultrahigh field transmit/receive arrays.

The coax monopole antenna is presented for body imaging at 7 T. The antenna is fed at one end, eliminating the possibility of cable-coil coupling and simplifying cable routing. Additionally, its flexibility improves loading to the subject. Like the coax dipole antenna, an interruption in the shield of the coaxial cable allows the current to extend to the outside of the shield, generating a B1 + field. Matching is achieved using a single inductor at the distal side, and a cable trap enforces the desired antenna length. Finite difference time domain simulations are employed to optimize the design parameters. Phantom measurements are conducted to determine the antenna's B1 + efficiency and to find the S-parameters in straight and bent positions. Eight-channel simulations and measurements are performed for prostate imaging. The optimal configuration is a length of 360 mm with a gap position of 40 mm. Simulation data show higher B1 + levels for the coax monopole (20% in the prostate), albeit with a 5% lower specific absorbance rate efficiency, compared to the fractionated dipole antenna. The S11 of the coax monopole exhibits remarkable robustness to loading changes. In vivo prostate imaging demonstrates B1 + levels of 10-14 μT with an input power of 8 × 800 W, which is comparable to the fractionated dipole antenna. High-quality images and acceptable coupling levels were achieved. The coax monopole is a novel, flexible antenna for body imaging at 7 T. Its simple design incorporates a single inductor at the distal side to achieve matching, and one-sided feeding greatly simplifies cable routing.

Revolutionizing healthcare with metamaterial-enhanced antennas: a comprehensive review and future directions

Abstract The state of the art for wearable antennas for wireless communication and biological applications is compiled in this article. It addresses a wide range of subjects, such as how to use novel materials like Artificial Magnetic Conductors (AMC) and Metamaterial (MTM) structures to enhance antenna performance. It also covers the design of dual-band and reconfigurable antennas and the use of machine learning to optimize aerial design. The main subject of this article is how wearable antennas could lead to advancements in wireless communication and healthcare in the future, perhaps improving lives worldwide. It includes implantable antennas, textile-based antennas, and various flexible graphene-based antenna varieties. The use of wearable antennas for brain stroke diagnostics, wireless body area networks, telemedicine, and breast imaging is covered in this study. Additionally covered are reconfigurable antennas based on Metamaterial (MTM)structures and Wideband on-body antennas inspired by Metamaterials (MTM), both of these applications are useful in the assembly of wearable antennas, which is the main goal of this work. The research also discusses how metamaterials (MTM) might raise the sensitivity of the bioelectric field, enabling precise bioelectric signal monitoring. Metamaterial (MTM) antennas function reliably in a range of biomedical applications and can adjust to the electromagnetic properties.

Design of a dual-band wearable flexible MIMO antenna system for ISM band applications

Abstract This article proposes a dual-band (2.4/5.8 GHz) wearable MIMO antenna system that can be applied to the ISM band. The antenna element uses an improved coplanar waveguide feeding structure. The four-element antenna system achieves high isolation between antenna elements through the self-decoupling structure of the antenna element and the orthogonal placement. The use of a floating ground structure effectively suppresses back radiation. Through the combination of coplanar waveguide feeding and floating ground, the antenna not only has a low profile but also improves the front-to-back ratio of antenna radiation, reducing the SAR value. The antenna also uses felt as a flexible dielectric substrate and conductive cloth as a radiation element, making the antenna flexible.

A compact flexible four-element dual-band antenna using a unique defective ground decoupling structure for Sub-6 GHz wearable applications

A compact wearable four-element dual-band antenna with good isolation is presented here. The antenna constitutes of a circular monopole with slits and slots incorporated into it to generate dual-band function, and a unique defected ground structure (DGS) with vertical stubs to neutralize coupling current and enhance isolation. The proposed antenna has a dimension of 62 × 52 × 0.25 mm3, bandwidth of 3.8–4.43 GHz (15.31%) and 5.25–6.3 GHz (18.18%), and 5.2 dBi peak gain. The specific absorption rate (SAR) analysis in W/kg for 1/10 g tissue exhibits values of 0.877/0.356 at 4.1 GHz and 0.309/0.105 at 5.3 GHz respectively. The antenna radiation characteristics are analysed using characteristic mode analysis. Furthermore, the diversity parameters are investigated, and the antenna exhibits relatively good results with envelope correlation coefficient (ECC) < 0.02, diversity gain (DG) > 9.99 dB, total active reflection coefficient (TARC) < −10 dB, mean effective gain (MEG) ratio ∼0 dB, multiplexing efficiency (ME) < −0.5, and channel capacity loss (CCL) < 0.3 bps/Hz, indicating its suitability for real-time MIMO applications.

Flexible Textile Antennas for 5G Using Eco‐Friendly Water‐Based Solution and Scalable Printing Processes

AbstractFlexible textile antennas are important for wireless communication within the expansion of 5G and the Internet of Things (IoT), as it allows for their integration in daily life objects. However, achieving these functionalities in textiles is challenging because of limitations in the electronic performance, flexibility with scalable fabrication process. This paper presents two flexible textile antennas for wearable and non‐ wearable devices compatible with 5G technology created by printing highly conductive silver nanoparticle inks. Two textile substrates are explored, as the dielectric component, a 3D polyester, and a natural origin fabric, burel. The processes used are cost‐effective and scalable, with the antennas designed to operate at 3–3.5 GHz, maintaining their return loss performance even under bending deformation and washing cycles. By transferring the optimized devices into clothes and wall covering, a detailed analysis with experimental measurements of the textile‐based antenna for different operation scenarios is introduced. The work highlights the suitability of these antennas for wearable applications and their alignment with green wireless technologies, contributing to the advancement of sustainable wireless communication systems.

Packaging and Antenna-Assembled Hybrid Stacked PCB with Novel Vertical Transition for 39 GHz 5G Base Stations

This paper proposes a novel packaging and large-scale antenna-assembled structure for a printed circuit board (PCB) that reinforces productivity, facilitates cost reduction, and maintains reliability. This was achieved by splitting the antenna from the main board and packaging it into a radio-frequency integrated circuit. In addition, two innovative solutions—an externally attachable flexible PCB antenna and a PCB-embedded coaxial line—are introduced to overcome the degradation in antenna performance and vertical RF transition loss in the proposed low-cost hybrid PCB. First, the proposed externally attachable flexible PCB antenna and a parasitic aircoupled antenna, which were easily assembled on the PCB, achieved an antenna efficiency of 95% and an impedance bandwidth of 7 GHz. Second, the fabricated coaxial line exhibited enhanced impedance matching over a wide frequency range of 30–40 GHz and improved insertion loss of approximately 1.4 dB. Furthermore, the packaged antenna, composed of 256 dual-polarized antenna elements per stream, incorporated a 39 GHz CMOS-based 16-channel phased-array transceiver IC. The set-level beam-forming measurements were verified considering an effective isotropic radiated power of 55 dBm at boresight and a steering range &gt;±60°. In addition to being suitable for mass production in terms of cost and reliability, the proposed structures and solutions met the required antenna and beam-forming performance for commercial 39 GHz base stations without sacrificing performance.

Compact Sub-6 GHz Four-Element Flexible Antenna for 5G Applications

This paper proposes the design of a compact sub-6 GHz four-port flexible antenna for utilization in 5G applications. A two-arm monopole with a coplanar waveguide feed line printed on a flexible substrate was proposed to shape the single-element antenna. The single element was designed, fabricated, and measured first; then, four copies of the single element were organized on a single flexible substrate to compose the four-port antenna. The MIMO antenna was simulated, fabricated, and experimentally measured. All the simulations and measurements of the flexible single element and MIMO antennas are presented. The presented MIMO antenna showed good impedance characteristics, with a deep level of −24 dB from 3 to 4.12 GHz. The antenna had omnidirectional and bi-directional patterns in the φ = 0° and φ = 90° planes. As an important parameter evaluation for MIMO, the mutual coupling between the different ports was investigated. The diversity gain (DG), the total active reflection coefficient (TARC), the mean effective gain (MEG), the envelop correlation coefficient (ECC), and the channel capacity loss (CCL) parameters were investigated and showed good performance. All the obtained simulation results were in a high degree of agreement with the measurement results, supporting the usage of the suggested antenna in 5G communications.

Flexible Symmetric-Defection Antenna with Bending and Thermal Insensitivity for Miniaturized UAV.

Flexible conformal-enabled antennas have great potential for various developable surface-built unmanned aerial vehicles (UAVs) due to their superior mechanical compliance as well as maintaining excellent electromagnetic features. However, it remains a challenge that the antenna holds bending and thermal insensitivity to negligibly shift resonant frequency during conformal attachment and aerial flight, respectively. Here, we report a flexible symmetric-defection antenna (FSDA) with bending and thermal insensitivity. By engraving a symmetric defection on the reflective ground, the radiated unit attached to the soft polydimethylsiloxane (PDMS) makes the antenna resonate at the ISM microwave band (resonant frequency = 2.44 GHz) and conformal with a miniaturized UAV. The antenna is also insensitive to both the bending-conformal attachment (20 mm < r < 70 mm) and thermal radiation (20~100 °C) due to the symmetric peripheral-current field along the defection and the low-change thermal effect of the PDMS, respectively. Therefore, the antenna in a non-bending state almost keeps the same impedance matching and radiation when it is attached to a cylinder-back of a UAV. The flexible antenna with bending and thermal insensitivity will pave the way for more conformal or wrapping applications.

Advancing Cognitive Radio in 5G Networks: A Survey of Flexible and Reconfigurable Antenna Technologies

Abstract: Nowadays, the communication industry is looking for a cognitive radio platform that can be used to handle multiple frequency bands, utilize various transmission protocols and be reconfigurable. For spectrum allocation, two methodologies have been adopted for CR between users who are licensed (PU) and those who are not (SU). They are spectrum overlay and spectrum underlay. Secondary users need to operate below the principal users' noise level therefore, significant restrictions resisted on the strength of their transmission in spectrum underlay methodology. Spectrum underlay is a type of underlay that is used in the construction of the unoccupied section of the spectrum searched by CR in the spectrum overlay process. A reconfigurable antenna is needed on RF front-end side of CR, which will a range of completely to span a vast array of frequencies specified sub-bands of frequency, and this is often a major design challenge. An antenna with a flexible monopole for Ultra-wideband equipment competent to function between the frequency range of 3.1 GHz to 10.6 GHz. Designs of reconfigurable antennas reported in the literature are mostly observed to be capable of manual tuning or switching between two or a few frequency bands. Hence, the requirement of new designs of integrated UWB and reconfigurable narrowband antennas that operate from 2 GHz and up to 12 GHz frequency range with a high degree of automated tunability or switching facility into different narrow bands would have a strong application potential for CRs.

Exploiting FAS for Cooperative NOMA-based Full-duplex mmWave Networks with Imperfections

The primary constraints inherent in the millimeter wave (mmWave) technology manifest as high path loss and limited range. As a result, a line-of-sight environment is necessary for a seamless connection between source and destination nodes. At the same time, the prevalence of intervening obstacles becomes increasingly pronounced, owing to the escalating densification of contemporary wireless networks. We address these inherent challenges by exploring the aid of non-orthogonal multiple access (NOMA) and fluid antenna system (FAS) technologies. Our proposed approach centers around deploying an N-user NOMA network for optimizing the base station’s resources and facilitating cooperative full-duplex communication. Furthermore, the integration of L-port FAS elevates the quality-of-service by designing a flexible and compact antenna tailored to meet the needs of mobile users. Most works ignore the imperfections of transceiver hardware that is critical for high-rate communication systems. In this work, we have considered both ideal and non-ideal transceiver hardware to analyze the importance of practical systems. The findings indicate that ten-port FAS performs better than the selection-combining diversity. Still, it necessitates approximately 600 ports to surpass the capabilities of a four-antenna maximum-ratio-combining scheme. Ultimately, we formulate the expressions for outage probability, considering residual self-interference, residual transceiver hardware impairment noise, and interference, and corroborate these expressions through Monte Carlo simulations.

C-band Hexagon Slotted Textile Antenna Design with Jeans Substrate for Satellite Communication Applications

This paper presents the design of a hexagonal slotted circular flexible textile microstrip patch antenna that is used for C-band satellite communication applications. In the proposed antenna design, a textile material blue Jeans fabric with relative permittivity 1.67, loss tangent of 0.01 and the thickness of 1 mm is used as the substrate with an overall dimension of 40×38 mm2. The textile material is used as it is washable, wearable, flexible and very economical. Self-adhesive Copper tape is used to make the patch and ground of the antenna that is fed through a microstrip inset feed line. The proposed antenna contains a hexagonal-shaped slot on the patch and a partial ground configuration for getting better bandwidth and gain. The antenna has been designed and simulated using CST microwave Studio software. The simulated antenna performance parameters like return loss, bandwidth, VSWR, gain, efficiency, radiation pattern and surface current are presented. The antenna is resonating at 4.28 GHz and operating in the frequency range of 2.91 -5.2 GHz, with reflection coefficient of -24.42 dB, and a bandwidth of 2.29 GHz. The peak gain of the antenna is 3.42 dBi and radiation efficiency of 87.3% at 4.2 GHz. The proposed antenna covers C-band and with its compact size, wearability and wide bandwidth capabilities, the antenna proves to be a suitable candidate for C-band satellite communication applications.

A DODECAGON SLOTTED CIRCULAR TWO-ELEMENT SUB-6 GHZ FLEXIBLE ANTENNA FOR WEARABLE APPLICATIONS USING MODAL ANALYSIS

The sub-6 GHz 5G band has opened doors for a seamless and high-data-rate communication system connecting multiple devices. Multiple-input/multiple-output (MIMO) antennas are the backbone of such reliable communication systems with enhanced channel capacity. In this paper, a flexible two-element antenna is proposed for wearable applications. The dodecagon-slotted modified circular patch antenna with a defective ground structure gives isolation of 18 dB over the bandwidth. The antenna exhibits a gain of 3.38 dBi at the operating frequency of 4.8 GHz. A characteristic mode analysis was performed to investigate the resonance behavior of the antenna. Furthermore, specific absorption rate analysis was performed and found to be 0.790/0.314 W/kg for 1/10 g of tissue at 4.8 GHz. The MIMO diversity metrics exhibited an envelope correlation coefficient &amp;#60; 0.001, total active reflection coefficient &amp;#60; -10 dB, diversity gain &amp;asymp; 10, mean effective gain &amp;#60; -3 dB, channel capacity loss &amp;#60; 0.40 bps/Hz, and multiplexing efficiency &amp;#60; 0 over the operating frequency band.

Functional plastic films: nano-engineered composite based flexible microwave antennas with near-unity relative visible transmittance

Functional plastic films: nano-engineered composite based flexible microwave antennas with near-unity relative visible transmittance

Design of X/Ku and K Band Flexible Cloud-Fractal Wideband Antenna with Bandwidth Estimation Using CMA

Design of X/Ku and K Band Flexible Cloud-Fractal Wideband Antenna with Bandwidth Estimation Using CMA

Flexible and Wearable Antenna for Biomedical Application: Progress and Opportunity

Flexible and Wearable Antenna for Biomedical Application: Progress and Opportunity

A Flexible UWB Slot Antenna with Quad Band-notched Characteristics for Wearable Application

A Flexible UWB Slot Antenna with Quad Band-notched Characteristics for Wearable Application