Textile Antenna Research Articles

Textile Bandwidth-Enhanced Polarization-Reconfigurable Half-Mode Substrate-Integrated Cavity Antenna.

A textile bandwidth-enhanced polarization-reconfigurable half-mode substrate-integrated cavity antenna was designed for wearable applications. A slot was cut out from the patch of a basic textile HMSIC antenna to excite two close resonances to form a wide -10 dB impedance band. The simulated axial ratio curve indicates the linear and circular polarization of the antenna radiation at different frequencies. Based on that, two sets of snap buttons were added at the radiation aperture to shift the -10 dB band. Therefore, a larger frequency range can be flexibly covered, and the polarization can be reconfigured at a fixed frequency by switching the state of snap buttons. According to the measured results on a fabricated prototype, the -10 dB impedance band of the proposed antenna can be reconfigured to cover 2.29~2.63 GHz (13.9% fractional bandwidth), and the circular/linear polarization radiation can be observed at 2.42 GHz with buttons OFF/ON. Additionally, simulations and measurements were carried out to validate the design and to study the effects of human body and bending conditions on the antenna performance.

Design and Fabrication of Waveguide Slot Antenna Using 3D Printing for 5G Application

This research constructs a 26 GHz waveguide slot antenna with decent gain. The application of millimeter-wave requires high bandwidth and gain to increase the traffic and users for millimeter-wave and 5G technology. The application of millimeter waves requires a high gain and bandwidth to achieve the requirements of traffic and users increasing for 5G technology and existing millimeter-wave. High-gain and power handling are provided by waveguide slot antennas. Three waveguide structures which are two waveguide antennae and a waveguide horn have been simulated by using CST and fabricated by a 3D printer. The tilt technique has been used with a waveguide to increase the bandwidth and gain of an antenna. A waveguide with broad wall tilt slots has one diction beam while a waveguide with broad and narrow wall tilt slots has two direction beams, each length of the wall enough to distribute six symmetric tilt slots. The gain of 14.3 dB and 1.9 GHz bandwidth are recorded for an antenna with broad wall tilt slots with one beam. While the waveguide with broad and narrow wall tilt slots achieved a gain of 13.9dB and a bandwidth of 1.9 GHz. The proposed antenna is a decent candidate for use with millimeter waves.

Two-port miniaturized textile antenna for 5G and WLAN applications

AbstractA compact, two-element textile MIMO antenna is designed with enhanced isolation by using modification in the ground, open-ended slots along with shorting pins. Maximum 27.8 dB isolation is achieved in two-element antennae, where the edge-to-edge distance is kept at 0.19 λ0 which is less than the conventional half wavelength. The Y-shaped decoupling and shorting pins improve the isolation up to 14 dB and can mitigate the current moment between the two ports effectively. The open slots in the ground are enhancing the mutual impedance and shift the operating band of the antenna toward the lower frequency band and thus size miniaturization is also achieved. The textile antenna achieves a 10 dB impedance bandwidth from 4.24 to 5.38 GHz with more than 21.1 dB isolation in the entire band. The phantom wrist model and bending analysis are carried out with the textile antenna to validate the on-body effects of the antenna in wearable and 5G applications.

Development of wideband CPW‐fed microstrip patch antenna on textile substrate

AbstractA wideband flexible coplanar microstrip patch (CPW) antenna is developed on a felt substrate to radiate from 1.4 to 3 GHz. The dimension of the antenna is 0.37λ × 0.37λ × 0.007λ, developed on felt, which is a flexible textile material with a 1.38 dielectric constant. The patch and ground are printed on the same side of the substrate, where a semi‐circular slot is etched on the patch, and symmetric slots are etched on the ground to achieve wide bandwidth (73%). CPW feed impedance is matched with the connector impedance using the modified feed line. The felt antenna has a measured peak gain of 4.7 dB at 2.45 GHz. Moreover, the performance of the textile antenna under different bending conditions are experimentally carried out. The antenna bandwidth is reduced due to a decrease in bending angle, but still, the antenna operates at the required bandwidth of 1.8–2.9 GHz (upto 80 mm radius).

High efficiency radio frequency antennas for amplifier free quantum sensing applications

Radio frequency (RF) signals are frequently used in emerging quantum applications due to their spin state manipulation capability. Efficient coupling of RF signals into a particular quantum system requires the utilization of carefully designed and fabricated antennas. Nitrogen vacancy (NV) defects in diamond are commonly utilized platforms in quantum sensing experiments with the optically detected magnetic resonance (ODMR) method, where an RF antenna is an essential element. We report on the design and fabrication of high efficiency coplanar RF antennas for quantum sensing applications. Single and double ring coplanar RF antennas were designed with −37 dB experimental return loss at 2.87 GHz, the zero-field splitting frequency of the negatively charged NV defect in diamond. The efficiency of both antennas was demonstrated in magnetic field sensing experiments with NV color centers in diamond. An RF amplifier was not needed, and the 0 dB output of a standard RF signal generator was adequate to run the ODMR experiments due to the high efficiency of the RF antennas.

Ultrawideband Compact Lightweight Biconical Antenna With Capability of Various Polarizations Reception for Modern UAV Applications

This article presents the results of numerical modeling, optimization, fabrication and performance measurements of a new biconical antenna for modern unmanned aerial vehicle (UAV) applications. The developed antenna effectively combines a set of fundamental constructive and electromagnetic requirements, which include compact structure and small total dimensions, lightweight, and ultrawideband operating frequency range with the capability of receiving or transmitting both circular, horizontal, vertical, and one of slant linear polarizations. For the first time, an effect of multiple resonance reflections in the structure of biconical antenna with a polarizer and deterioration of antenna’s matching and gain characteristics at a series of frequencies was detected by measurements. Theoretical analysis of the observed resonances has been carried out in this article. Possible ways to exclude resonances are given. In the most part of operating frequency range 2–18 GHz, the developed antenna provides voltage standing wave ratio (VSWR) less than 2 and gain higher than 3 dBi for the -45° slant polarization, while the +45° slant polarization is discriminated by more than 15 dB.

A simple design and fabrication of polarization reconfigurable antenna for industrial scientific and medical-band applications

<span lang="EN-US">This paper proposes a simple microstrip patch antenna (MPA) that can reconfigure its polarization states from linear to circular polarization in real-time by means of a PIN diode. An antenna is fed by a 50 Ω coaxial cable through the substrate of Teflon with relative permittivity of 2.15. The proposed antenna possesses a simple patch with a one-sided corner truncated to achieve polarization reconfigurability. A PIN diode is loaded to connect the main patch with a truncated corner and further maintain dual polarization states such as linear polarization (LP) and circular polarization (CP). Advanced design system (ADS) was used as a simulator to simulate the antenna, and a good understanding was obtained between simulated and measured results. Measured results showed a good agreement with simulated results at all working frequencies of interest. It shows minimum reflection coefficient gain with -10 dB scattering bandwidth 100 MHz for LP states and 170 MHz for CP states. It also shows an axial ratio of 1.56 dB for CP, and the cross-polarization level is also in a satisfying range.</span>

A Compact Coplanar Waveguide-fed Ultra-WidebandTextile Antenna for Wireless Body Area Network application

A compact CPW fed textile antenna is proposed for wireless body area network (WBAN) applications. It consists of rectangular shaped radiating patch with a stair case and ground plane and these two parameters have more impact on impedance bandwidth. The antenna is designed using the jean fabric material with size of 21 × 16 ×1 mm3and fabricated. The antenna has covered the desired UWB 3.1 - 10.6 GHz effectively. In addition, it has better radiation characteristics in both E-plane and H-plane. Antenna parametric study is done for various antenna parameters. It can be used for telemedicine and military applications.

ISM Band 2.4 GHz Wearable Textile Antenna for Glucose Level Monitoring

Wearable technology has recently attracted much interest for various uses. An essential component of the wearable system is the wearable antenna. Textile and non-textile materials have both been used to create wearable antennas. Textile antennas are very useful and widely used nowadays, particularly in body-worn applications monitoring health parameters. Fabricated using microstrip technology, textile antennas have various benefits, including small size, lightweight, simple fabrication, and ease of wear. In this study, a microstrip antenna is created utilizing a substrate made of jeans. It works between 2.4 to 2.5 GHz in the ISM (industrial, scientific, and medical) band. High-frequency structure simulator (HFSS) software was used to simulate two antennas, one with an incomplete and the other with a complete ground plane. Wearable antennas can protect the body from the impacts of RF radiation by utilizing the entire ground plane principle. Results from a vector network analyzer were obtained for the fabricated antenna (VNA). This antenna's main function is to track blood glucose levels. Blood's dielectric characteristics change when blood sugar levels fluctuate, affecting the antenna’s output frequency. There are two ways to monitor glucose levels. One method requires placing a finger on an antenna patch, while the other involves fixing an antenna to a person's arm and detecting the output frequency fluctuation. The antenna's resonant frequency raises in reaction to increased blood glucose levels. Therefore, these textile antennas are a great choice for non-blood sample monitoring of blood glucose levels.

Wearable coupled-quarter-mode SIW antenna platform with hybrid kinetic and ambient-light energy harvesting

As key enablers for smart fabric interactive textile (SFIT) systems, textile antenna systems and platforms need to be energy-efficient, low-profile and should guarantee a stable wireless body-centric communication link. Using multiple energy harvesters on and in the antenna platform is highly recommended to enable autonomous SFIT systems. Different sensors could be added to the system for monitoring the environmental and/or biophysical parameters of rescue workers, military personnel, and other safety workers. Therefore, a wearable coupled-quarter-mode (coupled-QM) substrate-integrated waveguide (SIW) antenna with optimally, seamlessly integrated hybrid kinetic and ambient-light energy harvesters is proposed. Two QM cavities are coupled via a non-resonant slot to create a compact antenna covering the [2.4; 2.4835] GHz Industrial, Scientific and Medical (ISM) band. The antenna platform fully consists of textile materials, being protective rubber foam and copper taffeta, enabling its unobtrusive integration into protective clothing. A novel, compact way of deploying a kinetic energy harvester inside the substrate, combined with flexible power management electronics on the antenna feed plane and a flexible ambient-light photovoltaic cell on the antenna plane, is proposed. The integrated antenna platform exhibits a measured impedance bandwidth of 307 MHz, a radiation efficiency of 88.57% and maximum gain of 3.74 dBi at 2.45 GHz. Wearing the antenna platform around a person’s wrist resulted in an average harvested power of 229.8 µW when walking in an illuminated room.

Flexible and Small Textile Antenna for UWB Wireless Body Area Network

In this paper, a miniaturized textile microstrip antenna is proposed for wireless body area networks (WBAN). The ultra-wideband (UWB) antenna used a denim substrate to reduce the surface wave losses. The monopole antenna consists of a modified circular radiation patch and an asymmetric defected ground structure, which expands impedance bandwidth (BW) and improves the radiation patterns of the antenna with a small size of 20 × 30 × 1.4 mm3. An impedance BW of 110% (2.85–9.81 GHz) frequency boundaries was observed. Based on the measured results, a peak gain of 3.28 dBi was analyzed at 6 GHz. The SAR values were calculated to observe the radiation effects, and the SAR values obtained from the simulation at 4/6/8 GHz frequencies followed the FCC guideline. Compared to typical wearable miniaturized antennas, the antenna size is reduced by 62.5%. The proposed antenna has good performance and can be integrated on a peaked cap as a wearable antenna for indoor positioning systems.

A Review of Clothing Components in the Development of Wearable Textile Antennas: Design and Experimental Procedure.

Wearable antenna systems have attracted significant research efforts during the last decade and a rich pool of review papers can be found in the literature. Each scientific work contributes to various fields of wearable technology focusing, mainly, on constructing materials, manufacturing techniques, targeting applications, and miniaturization methods. In this review paper, we examine the use of clothing components in wearable antenna technology. By the term "clothing components" (CC), dressmaking accessories/materials such as buttons, snap-on buttons, Velcro tapes, or zips are considered. In light of their utilization in the development of wearable antennas, the clothing components can play a triple role: (i) that of a clothing item, (ii) that of an antenna part or the main radiator, and (iii) that of an integration means of the antennas into clothes. One of their advantages is that they consist of conductive elements, integrated into the clothes, which can be effectively exploited as operating parts of wearable antennas. This review paper includes classification and description of the clothing components used so far in the development of wearable textile antennas with an emphasis on designs, applications and performance. Furthermore, a step-by-step design procedure for textile antennas that use clothing components as a functional part of their configuration is recorded, reviewed, and described in detail. The design procedure takes into account the detailed geometrical models required for the clothing components and the way they are embedded into the wearable antenna structure. In addition to the design procedure, aspects of experimental procedures (parameters, scenarios, and processes) that should be followed in wearable textile antennas with an emphasis on antennas that use clothing components (e.g., repeatability measurements) are presented. Finally, the potential of textile technology through the application of clothing components into wearable antennas is outlined.

Elastomeric Textile Substrates to Design a Compact, Low-Profile AMC-Based Antenna for Medical and IoT Applications

A neoteric, compact, low-profile, wide-band elastomeric textile antenna for medical and IoT applications is presented. The design synthesis of flexible artificial magnetic conductor (AMC)-integrated antenna is done using stratum of textile and operates within 4.76–6.08 GHz covering the 5.8-GHz industrial, scientific, medical (ISM) and 5-GHz Wi-Fi band for IoT applications. The rectangular fed design operates in the high frequency band which is widened and optimized to operate in the lower 5-GHz band and the notch etched with the monopole’s edges, suppress the cross-polarization component. The suggested design features an impedance bandwidth of 24.4% with a high gain of 10.59 dBi and has a compact footprint of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.44\lambda _{0}\times $ </tex-math></inline-formula> 0.46 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{0}\times $ </tex-math></inline-formula> 0.0512 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{0}$ </tex-math></inline-formula> . Simulation and experimental studies provide evidence that in the case of structural deformities, such as bending and crumpling and also for human body loading, the suggested AMC-integrated antenna is stable and shows superior efficiency relative to the traditional monopole antenna. Thus, to a large extent, the antenna is stable to maintain its radiation properties. Furthermore, numerical analysis demonstrates maximum amount of the specific absorption rate (SAR) is 0.0832 W/Kg according to IEEE standard safety guidelines. The advantage of the suggested AMC-integrated antenna design is that it is resilient to moisture conditions and the enhancement in impedance bandwidth is achieved by simple cut edges in the radiator and the ground plane leading to a simple staircase design. In addition, the simulation and measurement results are consistent, thus confirming it to be a promising contender for sensing and applications in body-centric wireless communications and Internet of Things.

Embroidered Annular Elliptical E-Textile Antenna Sensor for Knee Effusion Diagnosis

This article presents the design of a wearable textile antenna sensor for knee effusion diagnosis application. According to human anatomy, effusion is the collection of synovial fluid in a specific anatomic space. Knee effusion, often known as water on the knee, is a condition in which excess fluid collects around the knee joint. The antenna sensing patch region is embroidered using an automated computerized embroidery machine, while the design parameters were optimized using machine learning (ML) algorithms, including deep neural network (DNN). For the best fit on a knee joint, an annular elliptical structure of electronic textile (E-textile) antenna sensor is developed. Pure silver-coated highly conductive thread with improved flexibility is used for embroidering the patchwork in order to enhance the feasibility of the proposed device. The fabricated antenna sensor has the operating resonance frequency at 2.19 GHz and performs diagnosis based on the concept of reflection coefficient parameter. Furthermore, the specific absorption rate (SAR) level of a proposed sensor device is being evaluated on the knee joint and has been kept below the safety limit value of 1.6 W/kg averaged over 1 g of tissue model.

Graphene transparent antennas

Transparent antennas have attracted much attention because they can meet the demands of the Internet of Things (IoT) and fifth generation (5G) mobile communication technologies. From this point of view, intensive research and development has been carried out to produce materials with high optical transparency and low electrical resistance. Research on graphene transparent antennas is reviewed along with our experimental demonstration. The unique features of graphene as a material for transparent antennas are introduced and compared to the characteristics of metal-based and metal-oxide transparent conductors. The challenges involved in the fabrication of transparent antennas using graphene films grown by chemical vapor deposition (CVD) are described. Fabrication techniques of transparent antennas (transfer and patterning methods) and techniques to decrease the sheet resistance of the graphene films (stacking and doping methods) are described. The performance of the CVD graphene transparent antennas we have fabricated are presented.

Dual-Band Reconfigurable Flexible Antenna With Independent Frequency Tunability

A dual-band frequency-reconfigurable flexible textile and foam antenna with independent tunability is presented in this letter. The proposed antenna operates simultaneously in a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\text{TM}_{0(0.5)0}^{z}$</tex-math></inline-formula> mode and a higher order mode with individual frequency tunability centered at the 2.45 and 5.8 GHz industrial, scientific, and medical bands. The relative frequency tuning range at the lower band is 41.1%, while that at the higher band is 29.9%. The antenna is fabricated and measured to validate the concept. The antenna prototype operates as expected and maintains robust performance in various bending configurations through its individual dual-band frequency reconfigurability, which suggests its practicality for wearable applications.

Low specific absorption rate quad-port multiple-input-multiple-output limber antenna integrated with flexible frequency selective surface for WBAN applications

This paper presents the design and analysis of a multiple-input-multiple-output (MIMO) textile antenna for wireless body area network (WBAN) applications. The MIMO antenna is comprised of four identical modified rhombus-shaped monopole antenna elements of size of 0.57, where is the wavelength calculated at the lowest operating frequency. The antenna is backed by a 6 frequency selective surface (FSS) of dimensions of 0.84 to improve gain and to reduce specific absorption rate (SAR). The antenna has an impedance bandwidth (S 11 ⩽ −10 dB) of 8.8 GHz (2.8–11.6 GHz) and isolation of >19 dB between the resonating elements. In order to assess the MIMO antenna’s flexibility, the bending analysis is performed for various bending radii. The obtained diversity metrics are: envelope correlation coefficient <0.5 dB, diversity gain <10 dB, channel capacity loss <0.4 bits s−1 Hz−1, and total active reflection coefficient <−10 dB. The performance of the antenna with and without FSS is investigated for gain enhancement and SAR reduction. With the help of FSS, the antenna gain is increased to 8.44 dBi, and the SAR reduced from 6.99 Watt kg−1 to 0.0273 Watt kg−1. The FSS achieves the highest efficiency of 96%. The designed antenna is suitable for smart textile applications due to its low SAR, high gain, and wider impedance bandwidth.

Study of Helical Antenna Endowing Short Wire Length and Compact Structure for High-Frequency Operations and Its Exclusive Manufacturing Process

In this paper a study of a helical antenna resonating at high-frequency (HF) band with a very compact structure is reported. The designed antenna's S11 parameter magnitude change with frequency was calculated for different geometrical parameters. For each case, first, only a single parameter was changed. Then for a fair comparison, multiple parameters were changed simultaneously while the total wire length was set to be constant. Also, shifts in resonance frequencies and variations in -10 dB bandwidths were investigated. Our results show that resonance behaviour changes distinctively with the geometrical parameters and it allows shortening of the antenna wire length. For the designed antenna, the resonances shift to lower frequencies and -10 dB bandwidths around the resonances decrease as the winding wire thickness, number of turns, and turn radius increase. Whereas as the turn spacing increases the resonances shift to higher frequencies and -10 dB bandwidths widen, although the total wire length of the antenna increases. To verify the simulation results, the designed antenna was fabricated with an exclusive manufacturing process and characterized. The measurement results are in good agreement with the simulation results. It demonstrates the feasibility of the proposed manufacturing technique, which is new in the literature and enables accurate and rigid antenna fabrication with simple and low-cost steps.

Circularly Polarized Textile Sensors for Microwave-Based Smart Bra Monitoring System

This paper presents a conformal and biodegradable circularly polarized microwave sensor (CPMS) that can be utilized in several medical applications. The proposed textile sensor can be implemented in a Smart Bra system for breast cancer detection (BCD) and a wireless body area network (WBAN). The proposed sensor is composed of a wideband circularly polarized (CP) textile-based monopole antenna with an overall size of 33.5 × 33.5 mm2 (0.2 λo × 0.2 λo) and CPW feed line. The radiating element and ground are fabricated using silver conductive fabric and stitched to a cotton substrate of thickness 2 mm. In the proposed design, a slot is etched in the radiating element to extend bandwidth from 1.8 to 8 GHz at |S11| ≤ -10 dB. It realizes a circularly polarized output with AR ≤ 3 dB operation band from 1.8 to 4 GHz and an average gain of 6 dBi. The proposed CPMS's performance is studied both off-body (air) and on-body in proximity to breast models with and without tumors using near-field microwave imaging. Moreover, the axial ratio is recorded as a feature for a circularly polarized antenna and adds another degree of freedom for cancer detection and data analysis. It assists in detecting tumors in the breast by analyzing the magnitude of the electric field components in vertical and horizontal directions. Finally, the radiation properties are recorded, as well as the specific absorption rate (SAR), to ensure safe operation. The proposed CPMS covers a bandwidth of 1.8-8 GHz with SAR values following the 1 g and 10 g standards. The proposed work demonstrates the feasibility of using textile antennas in wearables, microwave sensing systems, and wireless body area networks (WBANs).

Conductive Ink Printed Fabric Antenna with Aperture Feeding Technique

Screen-printed and inkjet-printed conductive fabric antennas have been investigated in this manuscript. The former showed optimal radiation performance after fabrication and measurement, which was the basis for developing a new fabric antenna feeding technique. The aperture-fed technique is achieved with a single coaxial cable overlayed on a cut-out slot on the ground layer of the patch antenna. The cable is connected with conductive silver-based epoxy paste with high resilience to mechanical stress. Two antenna models for Bluetooth low energy (BLE) and long-range (LoRa) wireless applications were designed, fabricated, and measured at 2.44 GHz and 868 MHz, respectively, with good impedance and radiation performance. The measured antennas operated from 2.4 to 2.48 GHz (BLE) and 853 to 886 MHz (LoRa) at −10 dB S11. Measured results also showed a 56% radiation efficiency at BLE and 44.9% at LoRa. The screen-printing procedure and feeding technique have been presented in this manuscript.