Search Results (15)

We report on the effectiveness of using generative neural networks in an antenna design. We considered the modeling of microstrip antennas as they have significant advantages, such as a low profile, lightness, and ease of manufacture, which make them versatile for various applications. We designed, trained, and analyzed generative models applied to the modeling of these antennas without losing the generalizability of the application of these models to any antenna. We started with a Generative Adversarial Network (GAN), which was trained with data related to the antenna models for operation within the frequency range of 1 to 30 GHz. Using the synthetic data produced by the GAN resulted in antenna designs with dimensions and electromagnetic properties that were very close to the expected values. Next, a model was developed using a Conditional GAN (CGAN), which was trained to generate antenna characteristic data conditioned on an arbitrary central frequency, i.e., 2.4 GHz (generally used for Bluetooth, Wi-Fi, and ZigBee technologies), to enable better control over the process of generating these synthetic data. The CGAN model could satisfactorily generate synthetic data for this frequency range, simultaneously considering substrates with different dielectric permittivities. This study reveals that both generative models could produce synthetic data that were very close to the expected data, as evidenced by the low error values. Additionally, in terms of application, the models could provide both geometries and more than one antenna characteristic (resonance, bandwidth, and quality factor), which is very useful for direct application to practical designs. Full article

In this manuscript, we proposed the split ring resonator loaded multiple-input multiple-output (MIMO) antenna design for the frequency range of 1 and 25 GHz. The proposed antenna is numerically investigated and fabricated to analyze the different antenna parameters. We provided statistics on a wide range of antenna parameters for five different designs, including a simple circular patch antenna, a single-split-ring antenna, and a double-split-ring antenna. Reflectance, gain, directivity, efficiency, peak gain, and electric field distribution are all analyzed for all proposed antennas. The maximum achievable bandwidth is 5.28 GHz, and the double-split-ring resonator structure achieves this with a return loss of −20.84 dB. The radiation patterns of all the antenna with different port excitation conditions are presented to identify the behavior of the antenna radiation. We found the effect of the split-ring resonators to form radiation beams in different directions. We found the maximum and minimum half-power beam widths of 75° and 2°, respectively, among the different antenna designs. It was found that the split-ring resonator geometries in patch antenna convert wide-beam antenna radiation patterns to several narrow-beam radiation patterns. We found that each antenna’s bandwidth, gain, and return loss performance significantly differs from the others. Overall, the proposed results of the antenna may apply to a wide range of communication applications, including those for Wi-Fi, WiMAX, and 5G. Full article

Smart meters (SM) with wireless capabilities are one of the most meaningful applications of the Internet of Things. Standards like Zigbee have found a niche in transmitting data on energy usage to the user and the supplier wirelessly via these meters and communication hubs. There are still certain difficulties, notably in delivering wireless connectivity to meters situated in difficult-to-reach locations such as basements or deep indoors. To solve this issue, this paper investigates the usage of mesh networks at 868 MHz, particularly to increase coverage, and proposes an additional mounted antenna to significantly increase outside coverage while providing the necessary coverage extension for hard-to-reach indoor locations. Extensive measurements were made in Newbury in both suburban and open environments for validation and delivery of a simple statistical model for the 868 MHz band in United Kingdom conurbations. Results presented in this paper estimate that mesh networks at 868 MHz can accommodate large areas constituting several SMs with the proposed coverage extension method. With our findings and proposed methods on mesh connectivity, only 1% of UK premises will require mesh radios to achieve the desired coverage. Full article

Many authors suggest directional antennas to enhance the transmission performance of ZigBee networks. For line-of-sight propagation, directional antennas can extend the transmission range or reduce the transmit power. Directional antennas may also reduce interference between networks operating in the same frequency channel. However, these antennas may not perform similarly under non-line-of-sight propagation conditions. This work presents a study with ZigBee modules comparing the performance of a directional antenna with an omnidirectional one. The measurements were conducted on a university campus for different propagation outdoor environments. A deconvolution technique was applied to estimate the received signal as a function of the azimuth angle. The results demonstrated that the received power followed the gain difference between antennas only for paths with low attenuation. Considering the same Effective Isotropic Radiated Power (EIRP), the system with directional antennas started to lose packets at the same distance as the omnidirectional antennas. The directional antenna did not allow the increase in the link range compared to the omnidirectional antenna. The power consumption was also measured for different transmit power levels of the ZigBee radio. The study showed that the control circuits of directional antennas typically consume more power than omnidirectional antennas operating at a higher transmit power level. Full article

This article presents a quad-band multiple-input-multiple-output (MIMO) antenna for the Internet of Things (IoT) applications. The proposed antenna consists of four quarter-wavelength asymmetrical meandered radiators, microstrip feed lines, and modified ground planes. The antenna elements are arranged in a chiral pattern to improve isolation between them, with two radiators and two ground planes placed on the front side of the substrate and the other two on the back side. The MIMO antenna has an operating bandwidth (S₁₁ ≤ −10 dB) of 1.76–1.84 GHz, 2.37–2.56 GHz, 3.23–3.68 GHz, and 5.34–5.84 GHz, covering GSM, WLAN, WiMAX, and 5G frequency bands. The isolation between the radiating elements is greater than 18 dB in the operating bands. The peak gain of the antenna is 3.6 dBi, and the envelope correlation coefficient (ECC) is less than 0.04. Furthermore, the proposed antenna is validated for IoT-based smart home (SH) applications. The prototype MIMO antenna is integrated with a commercially available ZigBee device, and the measured values are found to be consistent with the expected results. The proposed MIMO antenna could be a good candidate for IoT systems/modules due to its low profile, compact size, lightweight, and easy integration with wireless communication devices. Full article

This article investigates the design, modeling, and fabrication of small-size (150 × 90 × 1.6 mm) broadband printed biconical antenna. The proposed antenna is intended for use a reference antenna for electromagnetic interference measurement inside the EMC chamber. The reflection coefficient (S11-parameter) is verified by modeling the equivalent circuit of the structure in terms of lumped elements. This structure offers a −10 dB impedance bandwidth (from 0.65 GHz to 2.3 GHz) with the tapered balun feeding method. Therefore, it has a high probability of estimating the electromagnetic waves emitted from several applications such as GSM, LTE, UMTS, 3G, Wi-fi, Bluetooth, ZigBee and more. The simulated standard antenna parameters are compatible with the measured parameters results. Furthermore, azimuth omnidirectional radiation pattern and well-realized gain (3.8 dBi) are achieved, reflecting good values of antenna factor compared to the commercial design. Full article

In this paper, an inverted F type antenna (IFA) for ZigBee communication of a sensor board has been designed and optimized, and it replaces the chip antenna on an RF (Radio Frequency) module that is not performing well enough for the ZigBee communication. The sensor board detects cattle behavior and identifies the breeding (estrus) period and transmits the data to the main station by the RF (Radio Frequency) module and IFA antenna. The proposed and optimized TRx (transmitting/receiving) IFA antenna of the ZigBee communication module has a return loss of −19 dB and a gain of 1.6 dB at 2.45 GHz. The size is about 2.5 × 0.5 cm in width and vertical length, and the height is 0.55 cm. The strength of signals with the chip antenna and the IFA antenna have been measured and compared. There is about a 20 dB enhancement with the IFA antenna compared to the chip antenna. The antenna is designed and applied to the RF transmission and reception (TRx) module. This antenna and sensor module can be applied to livestock in general as well as cattle. Full article

In the near future, the fifth-generation wireless technology is expected to be rolled out, offering low latency, high bandwidth and multiple antennas deployed in a single access point. This ecosystem will help further enhance various location-based scenarios such as assets tracking in smart factories, precise smart management of hydroponic indoor vertical farms and indoor way-finding in smart hospitals. Such a system will also integrate existing technologies like the Internet of Things (IoT), WiFi and other network infrastructures. In this respect, 5G precise indoor localization using heterogeneous IoT technologies (Zigbee, Raspberry Pi, Arduino, BLE, etc.) is a challenging research area. In this work, an experimental 5G testbed has been designed integrating C-RAN and IoT networks. This testbed is used to improve both vertical and horizontal localization (3D Localization) in a 5G IoT environment. To achieve this, we propose the DEep Learning-based co-operaTive Architecture (DELTA) machine learning model implemented on a 3D multi-layered fingerprint radiomap. The DELTA begins by estimating the 2D location. Then, the output is recursively used to predict the 3D location of a mobile station. This approach is going to benefit use cases such as 3D indoor navigation in multi-floor smart factories or in large complex buildings. Finally, we have observed that the proposed model has outperformed traditional algorithms such as Support Vector Machine (SVM) and K-Nearest Neighbor (KNN). Full article

An ultrathin, compact ecofriendly antenna suitable for IoT applications around 2.45 GHz is achieved as a result of exploring the use of Tencel fabric for the antenna’s design. The botanical ecofriendly Tencel is electromagnetically characterized, in terms of relative dielectric permittivity and loss tangent, in the target IoT frequency band. To explore the suitability of the Tencel, a comparison is conducted with conventionally used RO3003, with similar relative dielectric permittivity, regarding the antenna dimensions and performance. In addition, the antenna robustness under bent conditions is also analyzed by measurement. To assess the relevance of this contribution, the ultrathin ecofriendly Tencel-based antenna is compared with recently published antennas for IoT in the same band and also, with commercial half-wave dipole by performing a range test on a ZigBee-based IoT testbed. Full article

In this contribution, a narrowband radio channel model is proposed for rural scenarios in which the radio link operates under near-ground conditions for application in wireless sensor networks dedicated to smart agriculture. The received power attenuation was measured for both transmitter and receiver antennas placed at two different heights above ground: 0.2 and 0.4 m. Three frequency ranges, proposed for future 5G-IoT use case in agriculture, were chosen: 868 MHz, 2.4 GHz and 5.8 GHz. Three ground coverings were tested in a rural scenario: soil, short and tall grass fields. The path loss was then estimated as dependent of the radio link range and a three-slope log-normal path loss model was tailored. Results are explained in terms of the first Fresnel zone obstruction. Commercial Zigbee sensor nodes operating at 2.4 GHz were used in a second experiment to estimate the link quality from the experimental Radio Signal Strength Indicator (RSSI) received values. Two sensor nodes were placed at the same elevation above ground as in the previous experiment, only for short grass field case. The Quality of Service performance was determined in terms of theoretical bit error rate achieved for different digital modulations—BPSK, 8PSK and 16QAM—concluding remarkable results for an obstructed radio link. Full article

In this contribution, we present a narrowband radio channel model for a scenario wherein the radio link operates under near-ground conditions, occurring on a ZigBee wireless sensor networks applied to smart agriculture. A near-ground network deployment can be useful to avoid tall antenna masts, or once crops grow. Among the examined scenarios, we analyzed path loss caused when placing sensor nodes in soil, short and tall grass fields. We measured the received power when locating both transmitter and receiver antennas at two different heights. The path loss was then estimated as dependent of the radio link range. In another scenario, RSSI were obtained to analyze the communication quality between sensor nodes using same antennas heights as the previous scenarios, only for the case of a short grass field. Full article

Due to the increasingly growth in population, it is important to better use natural resources for food production and efficiency, driving the use of sensors each time more to monitor several aspects of the soil and of the crops in the field. However, it is known that the harsh conditions of the field environment demands more robust and energy efficient sensor devices. One example is soil water monitoring for irrigation: Brazil, for example, consumes 69% of its freshwater only for irrigation purposes, which shows the need of using adequate water moisture sensors. Based on that, this work proposes a modular architecture that integrates several sensor technologies, including battery-less sensors and low power sensors for soil moisture measurements, but not limited to them. The proposed system relies on a mobile robot that can locate each deployed sensor autonomously, collect its data and make it available on-line using cloud services. As proof of concept, a low-cost mobile robot is built using a centimeter level accuracy location system, that allows the robot to travel to each sensor and collect their data. The robot is equipped with an UHF antenna to provide power to RF powered battery-less sensors, a Bluetooth low energy data collector and a Zigbee data collector. An experimental evaluation compares reading distance and successful rate of sensor location and reading. Full article

It is reported that wearable electronic devices are to be used extensively in the next generation of sensors for sports and health monitoring. The information obtained from sensors on the human body depends on the biological parameters, the measurement rate and the number of sensors. The choice of the wireless protocol depends on the required data rates and on system configurations. The communication link quality is achieved with narrowband technologies such as Bluetooth or Zigbee, provided that the number of sensors is small and data rates are low. However, real-time measurements using wideband channels may also be necessary. This paper reports narrowband link performance at 2.45 GHz for comparison with two UWB channels centered at 3.95 GHz and 7.25 GHz. A monopole antenna covering 2.45 GHz and UWB is optimized for an on-body communication link between the footwear and the wrist. The cumulative distribution function of several path loss measurements is reported and compared for a subject standing and walking. Results show that the larger bandwidth in the UWB channel reduces fading and stabilizes the channel predictability. Full article

Body sensor networks (BSN) are an important research topic due to various advantages over conventional measurement equipment. One main advantage is the feasibility to deploy a BSN system for 24/7 health monitoring applications. The requirements for such an application are miniaturization of the network nodes and the use of wireless data transmission technologies to ensure wearability and ease of use. Therefore, the reliability of such a system depends on the quality of the wireless data transmission. At present, most BSNs use ZigBee or other IEEE 802.15.4 based transmission technologies. Here, we evaluated the performance of a wireless transmission system of a novel BSN for biomedical applications in the 433MHz ISM band, called Integrated Posture and Activity NEtwork by Medit Aachen (IPANEMA) BSN. The 433MHz ISM band is used mostly by implanted sensors and thus allows easy integration of such into the BSN. Multiple measurement scenarios have been assessed, including varying antenna orientations, transmission distances and the number of network participants. The mean packet loss rate (PLR) was 0.63% for a single slave, which is comparable to IEEE 802.15.4 BSNs in the proximity of Bluetooth orWiFi networks. Secondly, an enhanced version is evaluated during on-body measurements with five slaves. The mean PLR results show a comparable good performance for measurements on a treadmill (2.5%), an outdoor track (3.4%) and in a climate chamber (1.5%). Full article

A main application in radio frequency identification (RFID) sensor networks is the function that processes real-time tag information after gathering the required data from multiple RFID tags. The component technologies that contain an RFID reader, called the interrogator, which has a tag chip, processors, coupling antenna, and a power management system have advanced significantly over the last decade. This paper presents a system implementation for interoperation between an UHF RFID reader and a TCP/IP device that is used as a gateway. The proposed system consists of an UHF RFID tag, an UHF RFID reader, an RF end-device, an RF coordinator, and a TCP/IP I/F. The UHF RFID reader, operating at 915 MHz, is compatible with EPC Class-0/Gen1, Class-1/Gen1 and 2, and ISO18000-6B. In particular, the UHF RFID reader can be combined with the RF end-device/coordinator for a ZigBee (IEEE 802.15.4) interface, which is a low-power wireless standard. The TCP/IP device communicates with the RFID reader via wired links. On the other hand, it is connected to the ZigBee end-device via wireless links. The web based test results show that the developed system can remotely recognize information of multiple tags through the interoperation between the RFID reader and the TCP/IP device. Full article