Numerical Design of Ultra-Wideband Printed Antenna for Surface Penetrating Radar Application

Surface penetrating radar (SPR) is an imaging device of electromagnetic wave that works by emitting and transmitting a narrow period pulse through the antenna. Due to the use of narrow period pulse, according to the Fourier transform duality, therefore ultra-wideband (UWB) antenna becomes one of the most important needs in SPR system. In this paper, a novel UWB printed antenna is proposed to be used for SPR application. Basically, the proposed antenna is developed from a rectangular microstrip antenna fed by symmetric T-shaped. Some investigation methods such as resistive loading, abrupt transition, and ground plane modification are attempted to achieve required characteristics of bandwidth, radiation efficiency, and compactness needed by the system. To obtain the optimum design, the characteristics of proposed antenna are numerically investigated through the physical parameters of antenna. It is shown that proposed antenna deployed on an FR-4 Epoxy substrate with permittivity of 4.3 and thickness of 1.6mm has a compact size of 72.8mm x 60.0mm and a large bandwidth of 50MHz-5GHz which is suitable for SPR application

Ultra-Miniaturized Dual-Band Implantable Antenna for Wireless Capsule Endoscopy

This study introduces a small dual-band implantable antenna designed for Wireless Capsule Endoscopy (WCE). This antenna operates in the Wireless Medical Telemetry Service (WMTS) 1.4 GHz as well as the Industrial, Scientific, and Medical (ISM) 2.45 GHz bands. The designed antenna achieves miniaturization by employing open-ended slots, shorting pins, and arc-shaped slots on the radiating patch. The final structure has a compact size of 8.2 x 8.2 x 0.635 mm 3 . Homogeneous muscle and heterogeneous human phantoms are used to analyze the antenna’s behavior. The measurements are conducted by implanting the WCE device within minced pork meat. Considering the capsule’s deep location, the proposed antenna achieves gain values of -29.4 dBi at 1.4 GHz and -30.4 dBi at 2.45 GHz, respectively. The measured impedance bandwidths are 7.2 % and 4.2 % at 1.4 GHz and 2.45 GHz, respectively. Results suggest that the proposed antenna can reliably establish wireless communication at distances greater than 10 meters with a 10 dB margin for both frequencies. The 10-g specific absorption rate (SAR) values are 4.77 W/kg and 6.07 W/kg at 1.4 GHz and 2.45 GHz, respectively

A Design Methodology for Sensing-Ready Concentric Rings-Based Chipless RFID Tags With Effective Spectrum Use and High Coding Capacity

This paper introduces an innovative strategy for the development of sensing-ready concentric rings-based chipless radio frequency identification (CRFID) tags. Our approach is marked by the novel use of exponentially increasing spacing, a significant departure from the conventional uniform spacing method. This innovative design results in an impressive 88.2% improvement in tag data encoding capacity compared to traditional designs. Importantly, our design framework not only advances the current state of CRFID tag technology but also methodically lays the foundation for future integration of high-resolution sensing capabilities. This is achieved by strategically utilizing the innermost ring as a prospective sensing site, complemented by the implementation of nulls for data encoding achieved through the addition of an extra ring at the tag’s outermost edge. Notably, all these features represent advancements that have not been demonstrated in previously published concentric rings-based CRFID tags. To empirically validate our methodology, we have developed and tested 18-bit example tags optimized for operation within the ultrawideband (UWB) spectrum, covering a range from 3.1 to 10.6 GHz. The radar cross-section (RCS) response of these tags exhibits well-distributed resonances, culminating in a high encoding capacity of 17.65 bits/λ2/GHz. Preliminary results using capacitors connected to the innermost ring underscore the future sensing potential of our tags, setting the stage for more advanced sensing implementations in subsequent research

Sub-GHz Wrist-Worn Antennas for Wireless Sensing Applications: A Review

With recent advances in wearable wrist-worn wireless sensing applications, the demand for smartwatches and wristbands is rapidly increasing due to their widespread adoption in applications such as smart health monitoring, security, and fitness tracking. Currently, these devices primarily operate in the 2.45 GHz band, leveraging the availability of Bluetooth and Wi-Fi wireless technologies. However, the use of Sub-GHz frequencies (e.g., 433 MHz, 868 MHz, 915 MHz, 923 MHz) for wearable systems has also gained interest due to the emergence of wireless technologies like long-range wide area network (LoRaWAN), narrowband-IoT (NB-IoT) and Sigfox, which offer the potential for long-range wireless communications and sensing applications. In recent times, there has been a notable surge in the commercial production of a variety of Sub-GHz wrist-worn wireless sensing devices for health monitoring and tracking applications. Nevertheless, communications at Sub-GHz frequencies present significant challenges in antenna design, primarily due to the practical size constraints of wrist-worn devices and the necessity for using electrically small antennas. This paper meticulously reviews wrist-worn Sub-GHz antennas reported in the literature, analyzing key antenna parameters such as antenna topology, size, impedance bandwidth, peak realized gain, radiation efficiency, and specific absorption rate (SAR). Additionally, it underlines antenna design challenges, limitations, current trends, and presents potential future perspectives. To the best of the author’s knowledge, there is currently no existing literature comprehensively reviewing Sub-GHz wrist-worn antennas. Therefore, this paper represents the inaugural effort to provide a comprehensive review in this specific domain

RF Energy Harvesting Techniques for Battery-less Wireless Sensing, Industry 4.0 and Internet of Things: A Review

As the Internet of Things (IoT) continues to expand, the demand for the use of energy-efficient circuits and battery-less devices has grown rapidly. Battery-less operation, zero maintenance and sustainability are the desired features of IoT devices in fifth generation (5G) networks and green Industry 4.0 wireless systems. The integration of energy harvesting systems, IoT devices and 5G networks has the potential impact to digitalize and revolutionize various industries such as Industry 4.0, agriculture, food, and healthcare, by enabling real-time data collection and analysis, mitigating maintenance costs, and improving efficiency. Energy harvesting plays a crucial role in envisioning a low-carbon Net Zero future and holds significant political importance. This survey aims at providing a comprehensive review on various energy harvesting techniques including radio frequency (RF), multi-source hybrid and energy harvesting using additive manufacturing technologies. However, special emphasis is given to RF-based energy harvesting methodologies tailored for battery-free wireless sensing, and powering autonomous low-power electronic circuits and IoT devices. The key design challenges and applications of energy harvesting techniques, as well as the future perspective of System on Chip (SoC) implementation, data digitization in Industry 4.0, next-generation IoT devices, and 5G communications are discussed

A concertina-shaped vibration energy harvester-assisted NFC sensor with improved wireless communication range

The explosive growth of wireless sensor platforms and their emerging wide range of application areas make the development of a sustainable and robust power source, an essential requirement to enable widespread deployment of these wireless devices. As a solution to this cardinal issue, this paper reports the design and fabrication of a resonant Vibration Energy Harvester (VEH) that comprises interleaved springs, manifesting a concertina shaped structure that can enable large mechanical amplitudes of oscillation. Within a relatively small footprint (9cm3), this concertina-VEH yields a large power density of 455.6μW/cm3g2 while operating at a resonant frequency of 75Hz. Additionally, the feasibility of the implemented VEH to support NFC based wireless sensor platform, that is yet uncharted, is also investigated in this work. A very low-power consumption Near Field Communication (NFC) wireless sensor node has been designed and developed for this purpose. The developed concertina VEH has been employed to power the electronics interface of this NFC sensor. Using mechanical energy derived from as low as 0.2g excitation, our study shows that the VEH can enhance the electromagnetic interaction between the transmitting antenna and the reader, resulting in a 120% increase in wireless communication range for the NFC sensor node. Such a high-performance energy harvester assisted NFC sensor node has the potential to be used in a wide range of Internet of Things (IoT) platforms as a reliable and sustainable power solution

Flexible antenna on polymer-conductive textile composite for epidermal electronics

In this paper, we investigate the applicability of polydimethylsiloxane (PDMS)-conductive textile composite for realization of a robust flexible antenna for skin-mounted applications. For this purpose, we present the design, manufacture, and testing of an ultra high frequency (UHF) 868 MHz loop antenna with the specified material. The antenna performance has been investigated through simulations and measurements on a human forearm phantom. Apart from having a low-profile implementation and being mechanically flexible, and thus comfortable for on-skin use, the novel antenna presented demonstrates a wide operating bandwidth with acceptable gain for epidermal electronics

Reduced graphene oxide for the development of wearable mechanical energy-harvesters: A review

The unique characteristics of graphene have generated a lot of interest in the research community. A concept of utilizing graphene and its derivatives in the development of energy harvesters has just appeared in recent decades. This paper focuses on the application of reduced graphene oxide (rGO), a graphene derivative, in the development of wearable mechanical energy-harvesters to enable self-powered wearable sensing systems. Harvesting of energy has been a state-of-the-art phenomenon due to the ever-increasing requirement of power to run the sensing systems. Flexible systems that used rGO to gather energy with intensities ranging from a few microwatts to a few hundreds of microwatts have been used. Some examples are presented, focusing on the class of piezoelectric and triboelectric-based energy harvesters, with descriptions of their material composition, manufacturing methods, operating principle, and performance. Finally, the challenges and drawbacks of rGO-based energy harvesters are discussed, along with some of the potential solutions

A conformal, dynamic pattern-reconfigurable antenna using conductive textile-polymer composite

A conformal antenna with electronically tuning capability of its radiation pattern between broadside and monopole-like patterns is proposed. The antenna is based on a proximity-fed circular patch, loaded with a ring patch and four rectangular slots. The design is planar without any use of rigid shorting posts or complex feeding network. The reconfigurability is achieved by activating and deactivating the slots using PIN diodes, to switch between TM02 (monopole-like mode) and perturbed TM02 distributions (broadside mode) of the antenna. For conformability, the antenna is fabricated using highly flexible PDMS-conductive fabric composite. All the antenna parts, including the RF switches, wires, and DC biasing circuit are fully encapsulated by PDMS to provide resilience against deformation and harsh environment. Investigations on the RF performance and mechanical stability of the antenna were conducted. Under various bendings, it was demonstrated that all the antenna components, including those for electronic switching, remained intact and in working order even under radius bending of 30 mm, thus maintaining good pattern reconfigurability and overall performance. When bent, the measured results at 5.2 GHz show a stable radiation performance relative to those of the flat case (i.e., maximum gain of 2.9 dBi and efficiency of 64% in broadside mode, corresponding to 1.75 dBi and 52% in monopole-like mode). To the best of our knowledge, all these features have never been demonstrated in previously published pattern reconfigurable antennas

Screen printed epidermal antenna for IoT health monitoring

In this paper, we investigate the applicability of screen printable elastic silver ink on thermoplastic polyurethane (TPU) substrate for the realization of a flexible/stretchable antenna for direct implementation on human skin. For this purpose, we present the design, manufacture, and testing of an ultra- high frequency (UHF) 868 MHz loop antenna with the specified material. The antenna performance has been investigated through simulations and measurements on a human forearm phantom, including indoor wireless communication tests, demonstrating its potential for short-range IoT health monitoring applications