ShieldIt Super Research Articles

MINIATURIZATION OF STACKED WEARABLE ANTENNA FOR 5G APPLICATIONS

Wearable antennas have significantly expanded the capabilities of electronic devices, as they can now be seamlessly integrated into clothing for user convenience. The advent of 5G has opened up possibilities for enhanced functionality, necessitating compact antennas with high gain for efficient data transmission. In this paper, a sub-6GHz 5G stacked wearable antenna is proposed. The choice of a rectangular patch structure was made for its simplicity and ease of fabrication. A comprehensive analysis of antenna design, progressing from a single layer to a multilayer configuration is explained. The antenna was designed using 1mm felt and Shieldit Super conductor, with a 50 Ω coaxial feed. The proposed stacked three-layer antenna, with substrate dimensions of 44 x 44 mm², achieves a gain of 2.7 dBi. Stacking the substrate and patch layer improves the antennas’ performance, especially the impedance bandwidth and gain. On top of that, the antenna dimensions were reduced to 57% while maintaining its performance. Bending tests conducted in both X- and Y-axes demonstrate that the antenna's performance remains within an acceptable range. Although the resonating frequency shifted to 3.4 GHz in 3 layers during bending in Y-axis, the gain was kept to 1.8dBi. Both measured and simulated results exhibit good consistency, with a slight shift observed in the case of the three-layer structure.

High gain multi-band circularly polarized wearable leaky wave zipper MIMO antenna

A miniaturized, multi-band, four-port wearable Multiple Input Multiple Output (MIMO) antenna is proposed, which contains a leaky wave textile antenna (LWTA) on denim (εr = 1.6, tanδ = 0.006) as substrate and Shieldit Super Fabric as conductor textile. The concept in this work involves incorporating the metal and plastic zipper into the garment to function as an antenna worn on the body. Simulations and measurements have been conducted to explore this idea. The LWTA has dimensions of 40 × 30 × 1 mm³. Every two ports are separated by a zipper with two different kinds of materials: Acetal Polymer Plastic (APP) and 90 % brass to improve the isolation, gain, and Impedance bandwidth. The antenna operates in the frequency ranges covering the L, C, S, and X bands. Additionally, diversity performance is evaluated using the Envelope Correlation Coefficient (ECC) and diversity gain (DG). Simulation and measurement findings agree well, with a maximum gain of 12.15 dBi, low Specific Absorption Rate (SAR) based on the standards, DG greater than 9.65 dB, circular polarization (CP), and strong isolation (<-23 dB) between each port. Since the antenna's characteristics do not change significantly under bending and when the zipper is opened, the proposed antenna is a viable candidate for body-centric wireless communications on the battlefield. For example, it can facilitate communication covering wireless local area network (WLAN) and fifth-generation (5G) communications.

A wideband flexible electro-textiles material linear-to-circular polarizing metasurface for S-band CubeSat

In this paper, a flexible linear-to-circular polarizer FSS-based surface made from a single layer of cloth is introduced. Two orthogonal strips serve as the foundation for the proposed structure's architecture, with a central aperture in the unit cell for the pico-satellites aimed towards the S-Band. A wearable material called Shieldit Super serves as the conducting fabric in the unit cell, while Felt serves as the substrate. For the working center frequency of 2.41 GHz, the unit cell size is 0.32λ × 0.26λ × 0.02λ. It has a 3 dB axial ratio bandwidth (ARBW) of 42.90% and an axial ratio of 0.08 dB at 2.41 GHz, which is very close to zero. In addition, the FSS metasurface provides a bandwidth of up to 56.84% with 90% conversion efficiency. The polarizing surface is then created by multiplying this unit cell by a 6 × 6 array. The proposed structure's performance is proven by placing it in front of a patch antenna operating at 2.41 GHz. In addition to efficiently converting linearly polarized waves into circularly polarized waves, the antenna's performance improved when paired with the polarizing surface, as measured by the realized gain, which went from 3.14 dBi to 7.33 dBi.

Wearable UWB Antenna-Based Bending and Wet Performances for Breast Cancer Detection

This paper proposed integrating the communication system on the garment, which can be utilized to detect breast cancer at an early stage by using an ultra-wideband (UWB) wearable antenna. Breast cancer is an abnormal cell that is located in the breast tissue. Early detection of breast cancer plays an important role, and it helps in the long term for all women. The proposed UWB wearable antenna successfully operates at 3.1–10.6 GHz under an acceptable reflection coefficient of −10 dB. The fabricated wearable antenna was made from Shieldit Super and felt both conductive and nonconductive wearable materials. Few measurement studies of bending angles have been carried out that covered 2°, 4°, 6°, 8°, and 10°. In addition, the performance of UWB antennas in wet environments is studied in four stages: in water, instantly wet, nearly dry, and entirely dry. There is good agreement between the measured and simulated outcomes. Based on the experimental results, the proposed antenna could be helpful for a home breast cancer detection system.

Gain Optimization of Low-Profile Textile Antennas Using CMA and Active Mode Subtraction Method

This paper presents an active mode subtraction method based on the characteristic mode analysis to estimate the forward directivity based on the difference in modal significance curves. This made the optimization of the antenna gain in the design process to be more efficient. To the best of the authors' knowledge, such method is innovative and proposed in literature for the first time. This method is derived on the basis that the total radiated field of the antenna, and consequently, the directivity is mainly contributed by the excited dominant modes. To demonstrate its effectiveness, three compact, planar, and wearable antennas with increasing complexity will be designed and optimized using this method. The first is a conventional circular patch antenna operating at 5.3 GHz, whereas the second one is a planar loop antenna operating at 3.08 GHz. The third design is a crown-shaped planar antenna (CPA) with a 3 × 3 artificial magnetic conductor (AMC) plane integrated underneath to reduce potential coupling effects from the body. All three antennas are made fully using textiles with the same thicknesses: felt fabric as its substrate and ShieldIt Super as its conductive textile. For all designs, the use of the proposed method, which is validated using the method of moments, has predicted the maximum direction of radiation and its respective gain at the desired frequencies with good accuracy. Besides that, the design of the AMC plane for the CPA is also optimized using CMA prior to the integration with the antenna and a leather wrist strap. Measurements of the final crown-shaped antenna design indicated a good agreement with simulations, with an operating bandwidth of more than 240 MHz, FBR of 15.73 dB and a directional radiation pattern outward from the body.

Artificial Magnetic Conductor to Enhance Microstrip Patch Textile Antenna Performance for WiMAX Application

A rectangular microstrip patch textile antenna with Artificial Magnetic Conductor (AMC) operated at the center frequency of 5.80 gigahertz (GHz) for Worldwide Interoperability for Microwave Access (WiMAX) application was designed and simulated using the CST Microwave Studio 2016 and fabricated in this study. The use of AMC could solve the inflexibility of FR4 substrate that limits human body movement and reduce the radiation scattered on the human body whilst increasing the antenna gain and directivity. The antenna consists of 5×5 square shape gap of AMC unit cells ground layer using ShieldIt Super, five substrate layers using cotton (viscose) fabric as well as patch layer and another ground layer using the same ShieldIt Super. AMC is a metamaterial that imitates the conduct of zero reflection phase of Perfect Magnetic Conductor (PMC) on the resonant frequency not evidently existed in nature. Overall, the antenna with AMC has the significant return loss, S11 below than -30 decibel (dB), gain improved to more than 8 dB, and directivity elevated to more than 9 dBi at resonant frequency near to 5.80 GHz, respectively.

Single layered swastika-shaped flexible linear-to-circular polarizer using textiles for S-band application

A new swastika-shaped single layered flexible linear-to-circular polarizer is proposed for Cube Satellite application in S-band. The proposed linear-to-circular polarizer is designed fully using ShieldIt Super conductive textile on a lightweight felt substrate. Principle of operation is discussed comprehensively with an equivalent circuit model and its interaction with different orthogonal polarized wave components along with a succinct study of surface currents in different polarizations. Another linear-to-circular polarizer implemented on Polydimethylsiloxane (PDMS) substrate is designed and compared with the textile-based design. A preliminary deployment scheme is also proposed and studied by analyzing its performance under different bending conditions. Both textile and PDMS structures are confirmed to be operational within the range of 2.39 to 2.45 GHz. The textile polarizer is then prototyped and validated to be exhibiting similar conversion efficiency (CE) of 98% (simulated) and 93% (measured) at 2.45 GHz. Moreover, the fractional bandwidth defined by their 90% CE limits are 7.35% (from 2.36 to 2.55 GHz) in simulations and 6.6% (from 2.36 to 2.52 GHz) in measurements. The resulting axial ratio produced is 1.4 dB (in simulations) and 2 dB (in measurements), indicated its suitability for S-band application.

A crossed dodecagonal deployable polarizer on textile and polydimethylsiloxane (PDMS) substrates

This paper presents the design of a flexible using two set of flexible material classes: polymer and textiles. ShieldIt Super conductive fabric and felt are used as the textile material, and its performance is compared with another version designed on a polydimethylsiloxane (PDMS) polymeric substrate. They are both built using a 4 × 4 dodecagonal unit element array backed by a rectangular patch, each sized at 54 × 64 × 3.34 mm3 (0.40λ × 0.34λ × 0.02λ) and 62 × 52 × 3.34 mm3 (0.35λ × 0.41λ × 0.02λ). Both of them are validated to be operational centered at 2.2 GHz with a measured conversion efficiency of more than 90% from 1.578 to 2.578 GHz (48.12%) for the textile prototype. The results of the bending investigations suggest that the deployment mechanism must ensure a flat polarizer condition to enable its optimal performance.

Analysis Reconfigurable Frequency Textile Antenna in Bending Condition

In this paper, the analysis of reconfigurable frequency textile antenna in bending conditions is presented. The antenna consists of a truncated rectangular patch and slotted ground plane made by ShieldIt Super. Felt fabric is used as an antenna substrate. The proposed antenna is capable to reconfigure at seven different states frequencies by using three PIN diodes. The Circular Polarization (CP) is achieved at the GPS operating frequency. Meanwhile, the proposed antenna operates as a Linear Polarization (LP) at high operating frequencies. The performances of antenna in bending conditions is analyze since the textile antenna usually attached on the body will easily bend due to the human body structures. Details of the simulation results for antenna in bending condition are discussed.

Branch-line coupler using PDMS and Shieldit Super fabric conductor

In this paper, a new 3-dB branch-line coupler using PDMS substrate and Shieldit Super fabric conductive material is presented. The Shieldit Super fabric has low resistance less than 0.1/sq. and resulting in good conductivity. Both the simulated and fabricated coupler circuits demonstrated a 3 ± 1 dB fractional bandwidth (FBW) for the coupling as a result of the microstrip-slot created at the ground is in the range of 4.69–7.22 GHz which stands for 42.2%; while the FBW for 90° ± 5°, phase balance is in the range of 5.10–6.94 GHz or 30.70%. Within this range, both the return loss and the isolation are kept below −10 dB.

Performance Characteristics of ‘Triangle-Like’ Shape Textile Antennas

This paper reports the performance characteristics of two antennas fabricated on two different types of substrates: polyester and cotton. Two different types of conductive textile materials are used in this work, which are Pure Copper Polyester Taffeta Fabric and Shieldit Super. The performance characteristics include reflection coefficient, radiation pattern and current distribution are examined. The impedance and radiation characteristics of the proposed antennas, as studied by both simulation and experiment, are satisfactory.

Design of a Broadband All-Textile Slotted PIFA

A new broadband textile based PIFA antenna structure designed for wireless body area network (WBAN) applications is presented. The new topology can be directly integrated into clothing. The study starts by considering three different materials: flexible copper foil, and ShieldIt Super and pure copper polyester taffeta conductive textiles. Bandwidth broadening is successfully achieved by implementing a novel and simple slot in the radiating patch. The measured reflection coefficient and radiation characteristics agree well with simulations. Moreover, radiation characteristics and bandwidth show satisfactory immunity against detuning when operating on-body, especially when placed on the back. To our knowledge, the proposed structure is the first fully fabric based slotted PIFA to be reported in open literature with high bandwidth (more than 46%) and reasonable gain (ca. 1.5 dB), to be used for multiple applications in the frequency band of 1.8 to 3.0 GHz.