Design of a Flexible Microstrip Antenna for BAN Applications

A flexible microstrip antenna is a compact antenna that can be coupled with the skin. However, such antennas require to be coupled with an intermediate matching liquid medium which makes the antenna bulky, complicated, and expensive. Body area network devices are wearable wireless devices/sensors that are used to get the information of a patient’s health in terms of physiological changes irrespective of location. A flexible layer made of Polyethylene is chosen as the substrate and a copper patch is levied upon it. This substrate layer lies in between two adhesive layers (GIL GML 1000).In this paper, flexible antennas are designed and simulated for Body area networks (BANs). The S11 parameter, VSWR value, Gain, and the radiation pattern of the antennas are compared. The polyethylene substrate is highly flexible and lightweight; therefore it would be an ideal material to be used as the substrate of the required antenna.

Research on High-Performance Antennas Based on Graphene Materials

With the rapid development of the Internet of Things and wearable electronic devices, China is about to enter the 5G era. The current materials have been difficult to meet the production needs of flexible antennas working in the 5G frequency band. Flexible antenna sensors have received widespread attention because they can detect signal changes caused by antenna deformation. In recent years, miniaturization and high sensitivity have been the development trend of flexible antennas. However, traditional metal materials have disadvantages such as high density, easy corrosion, and poor bending stability, Can no longer meet the further development of 5G frequency band flexible antennas. Therefore, it is necessary to find a light and flexible material to replace the traditional metal material. Graphene has excellent flexibility, conductivity, and stability, once discovered, it has aroused widespread concern among scientists. This article mainly conducts certain research on graphene material, hoping to contribute to the development of 5G in China.

The Impact of Bending on Radiation Characteristics of Polymer-Based Flexible Antennas for General IoT Applications

Flexible wearable wireless devices have found practical uses as their cost has fallen and Internet of Things applications have gained further acceptance. These devices are gaining further use and acceptance in the consumer and wearable space for applications such as logistical tracking and maintaining sensor information, including temperature, humidity, and location. In such applications, antennas are exposed to bending and crumbling. Therefore, flexible substrate antennas for use with polymer-based flexible devices are an important area of research that needs to be addressed. In this study, the bending capabilities of flexible polymer substrate antennas for general IoT applications were practically analyzed by fabricating flexible antennas on Polyethylene Terephthalate (PET), Polytetrafluoroethylene (PTFE) Teflon, and Polyvinylchloride (PVC) substrates operating at 2.45, 4.45, and 7.25 GHz frequencies. The basic premise was to investigate the flexibility and bending ability of polymer materials, and their tendency to withstand deformation. In the current paper, we start by providing an equivalent model for the flexible microstrip patch antenna under bent conditions, followed by outlining the process of designing flexible antennas on polymer substrates. Finally, the fabricated flexible antennas were tested in an anechoic chamber for various radiation characteristics such as reflection coefficients, operating frequency shifts, and impedance mismatch with the transmission line, under bending conditions up to 7 mm. The practical outcomes were then compared with our recent investigation on flexible polymer substrate antennas for wearable applications. This study provides a means to select a suitable polymer substrate for future wearable sensors and antennas with high bendability.

On human body transmission wearable diamond dipole antennas above engineered jackets

This paper presents the propagation of dual-band diamond dipole antenna on three various jackets. The jackets are purely fleece fabric with Shieldit fabric patches on top of it. The network analyzers with the flexible lossless coaxial cable are used to measure the communication of the antennas. The experiment involves a man with ideal body mass index (BMI) wearing the jackets by placing the flexible antennas on top of it. It is observed that the best on-body communication is by wearing the engineered jacket. The 10 dB improvements are observed when the antenna is positioned on top of engineered jacket contrast to the regular jacket. In other words, the performance of the antenna is also be determined by antenna placement. High transmission lossesses cause the antenna mismatch when the antennas are positioned above the full conductive jacket.

Flexible leather substrate dual-band wearable antenna with impact analysis on testing under wet condition for human rescue system

Wearable flexible antennas have yielded much attention in recent years because of their interesting features and capabilities for enabling flexible, lightweight, portable and low cost wireless communication. The proposed research work offers the design of the flexible wearable patch antenna with four single Split Ring Resonators (SRRs) using a leather substrate for better performance. The proposed antenna is designed and simulated with leather substrate at the operating frequencies of 0.99 GHz and 3.5 GHz. The antenna is fabricated and validated under free space (normal condition), partially wet, fully wet and dried after wet conditions using Vector Network Analyzer (VNA). Different parameters such as reflection coefficient, Voltage Standing Wave Ratio (VSWR) and gain of the fabricated antenna are measured, and they are compared with the simulation results. The validated results show that the performance of the proposed antenna under free space, partially wet, fully wet and dried after wet conditions is virtually equal. The Specific Absorption Rate (SAR) of this proposed antenna is also investigated for 10g tissues and the SARs are 0.0168763 W/kg and 0.69567 W/kg at the operating frequencies of 0.99 GHz and 3.5 GHz, respectively. As a result, its good performance in wet conditions along with low cost and ready availability of leather material means the proposed antenna can be used for human safety environments, especially in military applications, etc.

Fully Flexible, Polymer based Microwave Devices Part II: Flexible Antennas and Performance Evaluation

In this work, we have investigated polymer-based flexible antennas from commercial and modified polymers, which are competitive to rigid PCB technology. Classical designs of the patch and bow-tie antennas have been realized and showed that the realized gain can get up to 9.16dBi for the patch and 7.9dBi for the bow-tie antennas. The effects of the dielectric loss and conductivity on the antennas’ performance in S-band have been analyzed in order to find limits for further material engineering and the optimum trade-off between microwave and mechanical performance. The bending effects have been investigated, and it has been found that E-plane bend inside can boost the antenna gain from 8.6dBi to 10.1dBi with the frequency shift from 2.5 GHz to 2.4 GHz for the patch and 7.9dBi to 11.3dBi at 3.1 GHz for the bow-tie antennas. The non-classical π-shaped conductors’ edges lead to additional fringing fields, which have an effect on the antenna’s gain and can be explored and exploited for further performance improvements. The new recipes for low-loss, low-Dk dielectric materials, and chemical integration between conducting

On the Accuracy of Flexible Antennas Simulations

The performance of wearable and flexible antennas can be greatly affected by bending and crumpling. While these effects have been studied in the literature, the accuracy of simulation in these conditions should be considered. In this paper, the effects of accurate modeling of the excitation, and the supporting structures are investigated.

Fully Flexible, Polymer based Microwave Devices Part II: Flexible Antennas and Performance Evaluation

In this work, we have investigated polymer-based flexible antennas from commercial and modified polymers, which are competitive to rigid PCB technology. Classical designs of the patch and bow-tie antennas have been realized and showed that the realized gain can get up to 9.16dBi for the patch and 7.9dBi for the bow-tie antennas. The effects of the dielectric loss and conductivity on the antennas’ performance in S-band have been analyzed in order to find limits for further material engineering and the optimum trade-off between microwave and mechanical performance. The bending effects have been investigated, and it has been found that E-plane bend inside can boost the antenna gain from 8.6dBi to 10.1dBi with the frequency shift from 2.5 GHz to 2.4 GHz for the patch and 7.9dBi to 11.3dBi at 3.1 GHz for the bow-tie antennas. The non-classical π-shaped conductors’ edges lead to additional fringing fields, which have an effect on the antenna’s gain and can be explored and exploited for further performance improvements. The new recipes for low-loss, low-Dk dielectric materials, and chemical integration between conducting

Bending Analysis of Polymer-Based Flexible Antennas for Wearable, General IoT Applications: A Review

Flexible substrates have become essential in order to provide increased flexibility in wearable sensors, including polymers, plastic, paper, textiles and fabrics. This study is to comprehensively summarize the bending capabilities of flexible polymer substrate for general Internet of Things (IoTs) applications. The basic premise is to investigate the flexibility and bending ability of polymer materials as well as their tendency to withstand deformation. We start by providing a chronological order of flexible materials which have been used during the last few decades. In the future, the IoT is expected to support a diverse set of technologies to enable new applications through wireless connectivity. For wearable IoTs, flexibility and bending capabilities of materials are required. This paper provides an overview of some abundantly used polymer substrates and compares their physical, electrical and mechanical properties. It also studies the bending effects on the radiation performance of antenna designs that use polymer substrates. Moreover, we explore a selection of flexible materials for flexible antennas in IoT applications, namely Polyimides (PI), Polyethylene Terephthalate (PET), Polydimethylsiloxane (PDMS), Polytetrafluoroethylene (PTFE), Rogers RT/Duroid and Liquid Crystal Polymer (LCP). The study includes a complete analysis of bending and folding effects on the radiation characteristics such as S-parameters, resonant frequency deviation and the impedance mismatch with feedline of the flexible polymer substrate microstrip antennas. These flexible polymer substrates are useful for future wearable devices and general IoT applications.