Industrial Scientific Medical Band Research Articles

A novel wideband circularly-polarized microstrip antenna array based on DGS for wireless power transmission

The requirement for applications operating at a variety of frequencies in a unified wireless device has greatly enhanced in recent years. For this purpose, multi-functional wireless components are essential. This paper presents a new design of a wideband circularly-polarized microstrip antenna array with defected ground structure (DGS). A previous design was introduced which cover the C-band at 5.8 GHz and operates in the industrial scientific medical (ISM) band for wireless communication applications. The proposed antenna has excellent performances which include good input impedance matching with a fed of the circular polarization at 5.8 GHz. The proposed design is validated and optimized by adding a new design of defected ground structure. This aperture geometry enables the antenna to operate in a wideband. The obtained results show that the modified antenna has a good performance in terms of return loss, bandwidth, gain and radiation pattern and demonstrate that the proposed antenna offers a good solution for multi-standard wireless communication applications

Platform-Tolerant Nested-Slot RFID Tag Antenna Based on Jigsaw-Shaped Metasurface

A novel low-profile (<0.005 λ) jigsaw-shaped metasurface for platform-tolerant nested-slot radio frequency identification (RFID) tag antenna is proposed in this letter. It consists of a 4 × 4 array of rippled-edged patch units with a central through-via. Compared with the widely used patch-unit artificial magnetic conductor structure, the proposed jigsaw-shaped metasurface is proved to suppress the surface waves effectively and reflect the electromagnetic waves in phase in the industrial scientific medical band of 902–928 MHz, therefore, it could improve the frequency and radiation stability of the nested slot RFID tag antenna on different platforms, and enhance the radiation performance of the tag antenna. The prototype of the metasurface was fabricated and measured as an interlayer of the nested-slot RFID tag and different platforms. The measured operation frequency band remains stable, and the measured reading range has a range deviation of less than 8.7% on different platforms.

An AMC-Based Liquid Sensor Optimized by Particle-Ant Colony Optimization Algorithms

This paper proposes a liquid sensor based on artificial magnetic conductor. The artificial magnetic conductor structure is optimized numerically using particle-ant colony optimization algorithm to increase the freedom of structural optimization exploration while reducing the time consumption. In the optimization process, the resonant frequency is kept at 2.45 GHz to ensure that the operating frequency is within the industrial scientific medical (ISM) band. The optimized artificial magnetic conductor is combined with a broadband antenna to build a liquid sensor. The designed sensor is fabricated and tested by loading butan-1-ol, propan-2-ol, ethanol, methanol, and water. The liquid samples can be injected directly into the channel without the need for additional expensive microfluidic chip such as polydimethylsiloxane, thereby greatly reducing the fabrication cost. A maximum sensitivity of 3.48% and a wide application range up to 78 are achieved, verifying the potential of the proposed sensor for low cost and real time monitoring of liquid samples in practical applications.

Efficient wireless power transmission to remote the sensor in restenosis coronary artery

In this study, the researchers have proposed an alternative technique for designing an asymmetric 4 coil-resonance coupling module based on the series-to-parallel topology at 27 MHz industrial scientific medical (ISM) band to avoid the tissue damage, for the constant monitoring of the in-stent restenosis coronary artery. This design consisted of 2 components, i.e., the external part that included 3 planar coils that were placed outside the body and an internal helical coil (stent) that was implanted into the coronary artery in the human tissue. This technique considered the output power and the transfer efficiency of the overall system, coil geometry like the number of coils per turn, and coil size. The results indicated that this design showed an 82% efficiency in the air if the transmission distance was maintained as 20 mm, which allowed the wireless power supply system to monitor the pressure within the coronary artery when the implanted load resistance was 400 Ω.

An Efficient and Compact Monopole Antenna Backed With Square Loop EBG Structure for Medical Wireless Body Area Network Applications

AbstractIn this paper, a compact, low‐profile, and simple monopole antenna is presented that is operated at the frequency of 2.4 GHz in industrial scientific medical band. The monopole antenna is based on the simple rectangular microstrip patch with a rotated T‐shaped slot. Furthermore, a 2 × 2 electromagnetic band‐gap (EBG) array is used in this design to act as an isolator between the antenna and the human body, which additionally increases the performance of the proposed antenna. The final design has an overall size of only 0.9λg × 0.9λg × 0.034λg (60 × 60 × 2.3 mm3) where λg is the guided‐wavelength with respect to RO4003 substrate at the resonant frequency of 2.4 GHz. This can make the structure a good candidate for wireless body area network applications. A prototype of the designed EBG‐based antenna is fabricated over a widely available RO4003 substrate. The measurement results show a gain of 6.52 dBi, a front to back ratio of 12.12 dB, and a total efficiency of 79.87% around the resonant frequency. Furthermore, numerical studies are conducted to evaluate the specific absorption rate (SAR) of the proposed design, which shows by introducing the EBG structure, more than 96% reduction in SAR level is obtained. All simulations are carried out by CST microwave studio software.

A novel broadband monopole coplanar antenna configuration with circular polarization

In this paper, a novel construction of a wideband slotted monopole antenna supplied by a single coplanar waveguide (CPW) with circular polarization (CP) characteristic for the small wireless device is proposed and discussed. The circular polarized CPW antenna is intended for the Industrial Scientific Medical (ISM) band spanning at 2.45 GHz. It consists of a monopole-shaped patch with two oppositely facing corner gaps extending from the CPW signal strip into the middle of a square metal frame serving as the ground, incorporates a couple of L-shaped grounding strips surrounding two oppositely facing corners of the ground, and an L slot in the topside of the ground plane. The bandwidth of the antenna’s input impedance is widened through reconfiguring the necessary parameters of the reversed L-shaped grounding strips. The circularly polarization can be significantly achieved through cutting an upturned L-slot mostly in the topmost half of the ground. The proposed antenna has a size of 60600.74mm3. Two electromagnetic solvers have been used to examine and to optimize the proposed circuit. The final circuit of the circularly polarized CPW monopole antenna is fabricated and validated by measurements. The measured bandwidth concerning the return loss at -10 dB is about 1.30 GHz and for the axial ratio at 3 dB, it’s about 500 MHz.

Ultra-low profile solar-cell-integrated antenna with a high form factor

This paper presents an ultra-low-profile copper indium gallium selenide (CIGS) based solar cell integrated antenna with a high form factor. A tiny slot was etched from the solar cell to develop an ultra-low-profile solar-cell-integrated antenna. This tiny slot increases the form factor due to the small clearance area from the solar cell. A ground-radiation antenna design method was applied in which lumped elements were employed inside the tiny slot for antenna operation. Another substrate was used under the solar cell for designing the feeding structure with lumped elements connected to the tiny slot using via holes. A prototype was fabricated and measured to verify the operation of a built-in solar-cell antenna and validate the simulated results. The measured results demonstrate that the solar-cell-integrated antenna covers the entire frequency range of the Industrial Scientific Medical band, from 2.4 to 2.5 GHz, with a maximum gain of 2.79 dBi and radiation efficiency higher than 80% within the impedance bandwidth range. Moreover, the proposed design has an ultra-low-profile structure of only 0.0046 λo, where λo represents the free space wavelength at 2.45 GHz, and a high form factor of 99.1% with no optical blockage. The antenna and solar cell were designed to avoid affecting the performance of each other using the radio-frequency decoupler.

A novel design of circularly polarized pentagonal planar antenna for ISM band applications

This paper presents a new circular polarized micro-strip antenna with a pentagonal shape radiator. The proposed antenna is designed to operate in the industrial scientific medical (ISM) band at the frequency of 2.45GHz for Wireless applications. The antenna consists of a radiating pentagon patch with appropriate dimensions on the upper side of a dielectric substrate and a defective ground structure (DGS) on the other side. The pentagon patch is fed through a 50Ω microstrip line. The structure is implemented on an FR-4 substrate with a relative permittivity of 4.4, loss tangent equal to 0.025 and thickness 1.58 mm. The antenna is designed and simulated by using advanced design system (ADS) electromagnetic solver and the achieved results are validated by using another electromagnetic solver. The simulation results indicate that the designed circularly polarized (CP) pentagonal microstrip patch antenna gives good results in terms of the reflection coefficient, voltage standing wave ratio (VSWR) and, axial ratio of 1.025 at 2.45 GHz.

Indoor Positioning System Based on Global Positioning System Signals with Down- and Up-Converters in 433 MHz ISM Band.

In this paper, an indoor positioning system using Global Positioning System (GPS) signals in the 433 MHz Industrial Scientific Medical (ISM) band is proposed, and an experimental demonstration of how the proposed system operates under both line-of-sight and non-line-of-sight conditions on a building floor is presented. The proposed method is based on down-converting (DC) repeaters and an up-converting (UC) receiver. The down-conversion is deployed to avoid the restrictions on the use of Global Navigation Satellite Systems (GNSS) repeaters, to achieve higher output power, and to expose the GPS signals to lower path loss. The repeaters receive outdoor GPS signals at 1575.42 MHz (L1 band), down-convert them to the 433 MHz ISM band, then amplify and retransmit them to the indoor environment. The front end up-converter is combined with an off-the-shelf GPS receiver. When GPS signals at 433 MHz are received by the up-converting receiver, it then amplifies and up-converts these signals back to the L1 frequency. Subsequently, the off-the-shelf GPS receiver calculates the pseudo-ranges. The raw data are then sent from the receiver over a 2.4 GHz Wi-Fi link to a remote computer for data processing and indoor position estimation. Each repeater also has an attenuator to adjust its amplification level so that each repeater transmits almost equal signal levels in order to prevent jamming of the off-the-shelf GPS receiver. Experimental results demonstrate that the indoor position of a receiver can be found with sub-meter accuracy under both line-of-sight and non-line-of-sight conditions. The estimated position was found to be 54 and 98 cm away from the real position, while the 50% circular error probable (CEP) of the collected samples showed a radius of 3.3 and 4 m, respectively, for line-of-sight and non-line-of-sight cases.

A Long-Range and Self-Powered Intelligent Food Monitoring System Based on Far-Field Energy Harvesting and Pressure Measurement

Introduction In recent decades, food safety is becoming a top concern in the world because it is directly related to human health. According to World Health Organization statistics, about 550 million people are poisoned each year because of unsafe food consumption. One of the leading causes of foodborne illnesses is the consumption of rotten and expired foods. Therefore, the development of a food monitoring system is essential. Indeed, many studies have focused on developing battery-free food monitoring systems based on radio frequency energy harvesting (RFEH) technology due to its benefits such as durability, low cost, and safety for stored food [1]-[2]. The major disadvantage of these studies is that they estimated food quality using gas sensors, which require large energy consumption (typically over 10mW). Moreover, the gas sensors need a long time to heat up to obtain accurate sensor data. These drawbacks reduce the feasibility of implementing these systems in practice.This paper aims to develop a self-powered battery-free food monitoring system based on far-field RFEH technique and pressure measurement, which can overcome the problems with the conventional methods. Methods and Experiments The overview architecture of our proposed system is depicted in Fig.1. The self-powering capability of the sensor tag is provided by converting the radio wave transmitted from an RF generator into electrical signals. The antenna is the first component and plays a vital role in an energy harvesting system. To improve the received power and enhance the distance of power transfer, we have developed a printed Yagi-Uda Three element (driver, director, and reflector) because of its simplicity in design, high gain, compact size, and low cost [3]. The operating frequency of the antenna is chosen at the unlicensed Industrial Scientific Medical (ISM) band of 915MHz. Besides, in this study, we focus on monitoring the gradual increase of the air pressure inside the food container due to gas emission during food degradation. The air pressure sensor has ultra-low energy consumption and high precision, suitable for the limited energy condition of far-field RFEH system. Finally, we conduct a set of experiments with different sorts of food, such as pork, fish, and chicken, to demonstrate the feasibility of the proposed method. Results and Conclusions As a result, the designed Yagi antenna has a high gain of 6.54dBi in the direction of the maximum radiation, better than the isotropic antenna in some conventional systems that usually achieve about 1.7 dBi [1]. The reflection coefficient of the Yagi-Uda antenna achieved -26.8dB and voltage standing wave ratio (VSWR) better than 1.3 in approximately 60 band (890-950 MHz). At a distance of 6 meters, the harvested RF power reach -10.9dBm , and the rectifying voltage was obtained at 380mV , which is high enough for the tag to launch its functions. The sensor unit is designed with ultra-low power components and consumes only 300μW on average. The air pressure, temperature, and humidity data obtained from the sensor tag are used to evaluate and estimate the food quality, demonstrating the proposed method's effectiveness.

A Novel Subcarrier-Level Spectrum Sensing Method by Utilizing Fine-Grained Channel State Information in Wireless Networks

Traditionally, the channelization structures of wireless technologies (802.11/ZigBee/BLE) have been fixed. Each node content for the spectrum is assigned one channel with a specific bandwidth. However, classical channel-based spectrum sensing and sharing algorithms have great limitations to further optimize spectrum utilization when multiple IoT with different wireless technologies coexisting in the same environment. Therefore, exploring the fine-grained spectrum sensing algorithm becomes an essential work to further improve the spectrum utilization efficiency, especially in the Industrial Scientific Medical (ISM) band. This paper proposes Subcarrier-Sniffer, a novel subcarrier-level spectrum sensing and sharing method, which utilizes channel state information (CSI) to sense the fine-grained status of each subcarrier of the traditional channel. To evaluate the performance of Subcarrier-Sniffer, we implemented Subcarrier-Sniffer by USRP B200min, and the experimental results show that the accuracy of subcarrier-level spectrum sensing could achieve 100% in our settings that the distance between Subcarrier-Sniffer and the monitor is not greater than 7 m. Subcarrier-Sniffer could be applied in WiFi and ZigBee, WiFi and BLE, and WiFi and LTE-U coexisted environments for better spectrum utilization.

A CMOS Adaptive 433/900 MHz Differential RF Power Harvester with Wide-Dynamic Range for Wireless Powering

A wide-dynamic range high-efficiency differential RF-to-DC power converter for wireless power transfer (WPT) applications is presented. The architecture offers high power conversion efficiency (PCE) over a wide range of input powers by employing cross-coupled high-threshold rectifying devices with stacking diodes. The proposed rectifier uses the adaptive biasing technique to control the rectifying devices’ conduction and minimizes the leakage current of the feedback diodes by utilizing the dynamic body biasing. Compared to the conventional cross-coupled rectifier, the proposed rectifier has a [Formula: see text] dynamic range. A prototype of the proposed rectifier is implemented in 65-nm CMOS technology and occupies an area of 0.0148[Formula: see text]mm2. The rectifier achieves [Formula: see text][Formula: see text]dBm sensitivity for 1[Formula: see text]V output and a 79.4% peak PCE. A dynamic range of 17.3[Formula: see text]dB is achieved at the 433[Formula: see text]MHz in the Industrial Scientific Medical band (ISM band) with a 100-K[Formula: see text] load. Furthermore, the proposed design offers a peak PCE of 62.6% and a wide dynamic range of 16.1[Formula: see text]dB at the UHF 900[Formula: see text]MHz band with a load resistance of 100-K[Formula: see text].

A 24 GHz Microstrip Comb Array Antenna With High Sidelobe Suppression for Radar Sensor

In this letter, a compact microstrip comb array antenna with high sidelobe suppression is presented for a 24 GHz radar sensor. Based on the printed circuit board process, several series-fed microstrip comb lines are designed on the substrate to form linear antenna arrays. Chebyshev distribution is adopted for the nonuniform excitation of each antenna element to achieve a very low sidelobe level (SLL). The excitation amplitude is adjusted by tuning the feedline width between the adjacent elements. Under such circumstances, a slimmer array with a tapering distribution is realized. The proposed linear comb array consists of eight elements and is further extended to 8 × 2 and 8 × 8 planar arrays to meet different requirements. The proposed antenna arrays are verified by the simulation and measurement, which are in good agreement. The measured SLLs are better than -28 dB. The measured gains of 8 × 1, 8 × 2, and 8 × 8 comb arrays at 24.125 GHz are 12.2, 15.0, and 19.8 dBi, respectively. The return losses are better than 10 dB and the broadside gains remain stable within the regulated industrial scientific medical band from 24 to 24.25 GHz.

Water dielectric microstrip patch antenna: case study at ISM 2.4 GHz

ABSTRACT Transparent antennas are becoming important in the wireless field since they can be integrated in combination with solar cells placed underneath the transparent antenna to make the antenna system compact. In this regard, water is used in this study. The behaviour of a water dielectric patch antenna is presented to find the influence of the thickness of water and the type of water used on the efficiency, gain and radiation pattern of the antenna. The water patch antennas operate at the ISM (Industrial, Scientific, Medical) band of 2.4 GHz. Measured results are compared with a classical square patch made from copper where the water patch performs with a comparable efficiency and similar radiation patterns.

Switchable Dual-Band Dual-Sense Circularly Polarized Patch Antenna Implemented by Dual-Band Phase Shifter of ±90°

A switchable dual-band dual-sense (DBDS) circularly polarized (CP) patch antenna is reported in this communication, which is implemented by dual-band phase shifter of ±90°. The proposed antenna is comprised by two annular-ring radiators, four H-shape slots, and two phase-controlled feeding networks. Four H-shape slots offer desired isolation between two paths of each feeding network, and also improve the impedance matching performance in two bands. Each dual-feed network is shared by two operating radiators, supporting simultaneous dual-band functionality. Meanwhile, the dual-band phase shifter is enabled by the folded shorted stubs that provide broadband dual-CP radiation performance. Thus, for each feeding network, −90° and 90° phase differences between two orthogonal signals can be achieved in each band, respectively, so as to meet the requirements of opposite polarizations. Two pairs of single pole single throws (SPSTs) are added in the feeding networks to acquire switchable CP characteristic, meanwhile improving the isolation between two feeding networks. As a proof-of-concept, a switchable DBDS CP antenna prototype operating at 2.45 GHz/5.8 GHz industrial scientific medical (ISM) bands is prototyped and tested with a low profile of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.036~\lambda _{0}$ </tex-math></inline-formula> . By controlling two pairs of SPSTs, the proposed patch antenna can switch from the right-handed circular polarization (RHCP)/left-handed circular polarization (LHCP) state to the LHCP/RHCP state.

Dual-turn electrically coupled loop antenna for gastrointestinal capsules

A dual turn electrically coupled loop antenna is proposed to operate inside gastrointestinal capsules. The proposed structure is simple with a degree of freedom in design and compact size. In addition, it has low specific absorption rate (SAR) levels. Four different models have been designed to operate at industrial, scientific, medical (ISM) bands (433 MHz and 915 MHz). The first three antenna models with different sizes operate at the 433 MHz ISM band while the fourth antenna model operates at the 915 MHz ISM band. The primitive designs are performed by immersing the biocompatible-encapsulated prototypes inside the center of a cubic box of muscle phantom with an edge length of 100 mm. To mimic the realistic situation, the final designs were simulated inside a human torso model. As an experimental verification, a prototype has been fabricated and tested inside minced beef. The footprint size excluding the space in the core is 200 mm3. The peak SAR levels, averaged on 1 g, are 78.4, 51.8 and 81.67 W/kg for the three proposed antennas, respectively. The low SAR levels permit increasing the fed power to compensate medium losses in addition to obtain better imaging. The peak realized gains in muscle lie in the range of the other counterparts (− 19 dBi).

A Software Defined Radio-Based Prototype for Wireless Metrics Studies in IoT Applications

The spectrum has always been an essential resource of information for wireless communications. With the continued growth of Internet of things (IoT) and 5G, there is a demand to understand how the spectrum is used. One of the challenges of deploying IoT applications is the crowded spectrum in the unlicensed industrial scientific medical bands leading to rising coexistence problems between different wireless protocols. To overcome this congestion, hardware tools supporting spectrum sensing can be used to manage the spectrum more efficiently. In this context, this work presents a prototype that measures a set wireless metrics on raw wireless signals acquired with software defined radio (SDR) technology. This prototype aims to provide mechanisms to sense and monitor spectrum usage that can mitigate one of the issues that IoT faces, the interference being produced by having different technologies using at the same frequency channels. The prototype features configurable radio frequency parameter and programmable periodical tasks execution. It displays wireless metrics such as signal to noise ratio, cumulative density function and power spectral density. This prototype uses web and SDR technologies, highlighting the idea and feasibility of combining these two technologies. In addition, it demonstrates the possibility to obtain wireless metrics with a low-cost hardware based on open source tools in a platform where interaction, debugging and maintaining becomes intuitive and easier. Results of measurements of LoRa protocol signals are presented to demonstrate the capabilities of the prototype.

A novel ISM band reflector type applicator design for microwave ablation systems

ABSTRACT In this paper, a radiation performance improved novel applicator is proposed which is called as reflector type microwave applicator as a part of microwave ablation (MWA) system operating at 2.45 GHz with experimentally measured bandwidth of 300 MHz in Industrial Scientific Medical (ISM) band for the local extermination of tumor with highly localized microwave power. The design principle of MW applicator is based on the structural formation of coaxial transmission line fed dielectric loaded with the metallic circular reflector for the near field energy concentration inside the tumorous tissue. To generate localized electromagnetic waves, a novel reflector type microwave applicator is designed by placing an aluminum disk near the 10 mm dielectric radiator section. The proposed applicator design has been numerically studied with finite integration technique (FIT) in CST Microwave Studio to develop the near field radiation pattern affecting the ablation level of tumorous tissue. In the light of performed numerical calculations, maximum SAR (Specific Absorption Rate) value on 1.76 g tumorous sample can be achieved to 208 W/kg under 15 W microwave power accepted by proposed probe. The experimental results confirm that proposed applicator can be utilized highly localized MWA applicator for cancer treatment hence the surface temperature of cylindrical shaped tumor sample which has the dimensions of 14.4 mm diameter and 8 mm height reaches from 25 to 68.3°C in 10 min.

A novel type of wearable dual-band antenna based on coplanar waveguide feeding for wearable wireless communications

A flexible and compact coplanar waveguide feed (CPW-fed) wearable antenna is introduced for wireless wearable communications applications at the industrial scientific medical (ISM) band. The proposed antenna consists of copper, which is used as the radiation patch and ground planes printed on the same side of polyimide flexible substrate. The overall size of the antenna is 30 mm × 28 mm × 0.08 mm, the results show that the antenna can transmit and receive signals in two frequency bands of 1.89–2.67 GHz and 3.02–3.23 GHz, in which radiating properties are characterized and agree well with the simulation results. The antenna is bent in different directions to further investigate the reflection coefficient and corresponding effect on the antenna under bending. The center frequency of the antenna is slightly shifted towards higher and lower frequencies when antenna is bent in X-axis and Y-axis, respectively. Furthermore, the wearability of the antenna is verified when the antenna is placed on different parts of the human body such as wrist and chest. Hence, the proposed flexible antenna is a suitable candidate for wearable wireless communication applications.

Enabling Global Cooperation for Heterogeneous Networks via Reliable Concurrent Cross Technology Communications

Industrial Scientific Medical (ISM) band has become more and more crowded due to the ever-growing size of many mainstream technologies, e.g., Wi-Fi, ZigBee and Bluetooth. Though the coexistence issue has led to severe Cross Technology Interference (CTI), it provides great opportunities to better utilize the scarce bandwidth resources. A fundamental question is how to ensure harmonious and effective operations for different networks To exploit it, a novel global cooperation framework is proposed. In particular, our work enables reliable concurrent Cross Technology Communication (CTC) from Wi-Fi to Wi-Fi, ZigBee and Bluetooth commodity devices. Compared to existing CTC approaches, our scheme improves the communication efficiency significantly, and hence is the foundation for effective global cooperation. Based on the proposed CTC scheme, a unified Media Access Control (MAC) approach is introduced to cooperate CTC message transmission and reception for heterogeneous networks with different MACs. Three proof-of-concepts applications, e.g. global synchronization, global CTI coordination and global Location Based Service (LBS) broadcasting are discussed to fully leverage the benefits of global cooperation. Extensive evaluations show that compared with existing schemes, the proposed framework achieves 8.1 times lower synchronization error, 9 times lower packet delivery delay, and 2.7 times lower energy consumption for acquiring LBS message.