This article presents a broadband optical nano-antenna, which covers a broader range of optical communication wavelengths (666 to 6000 nm), used in nano-photonic applications. The proposed design is ...modeled and analyzed to obtain a satisfactory gain of up to 11.4 dBi for a single element-based antenna. The unique feature of the proposed antenna is the hybrid plasmonic waveguide-based feed, which receives the optical signal from the planar waveguide and redirects the signal out of the plane. The proposed antenna provides highly directional radiation properties, which makes it a suitable candidate for inter- and intra-chip optical communications and sensing applications. Moreover, an extension of the work is performed for an array configuration of the order 2 × 1 and 64 × 1, to increase the gain and directionality. Therefore, this shows that it can be equally useful for optical energy harvesting applications with a significant gain up to 26.8 dBi.
A low-profile frequency reconfigurable monopole antenna operating in the microwave frequency band is presented in this paper. The proposed structure is printed on Flame Retardant-4 (FR-4) substrate ...having relative permittivity of 4.3 and tangent loss of 0.025. Four pin diode switches are inserted between radiating patches for switching the various operating modes of an antenna. The proposed antenna operates in five modes, covering nine different bands by operating at single bands of 5 and 3.5 GHz in Mode 1 and Mode 2, dual bands (i.e., 2.6 and 6.5 GHz, 2.1 and 5.6 GHz) in Mode 3 and 4 and triple bands in Mode 5 (i.e., 1.8, 4.8, and 6.4 GHz). The Voltage Standing Waves Ratio (VSWR) of the presented antenna is less than 1.5 for all the operating bands. The efficiency of the designed antenna is 84 % and gain ranges from 1.2 to 3.6 dBi, respectively, at corresponding resonant frequencies. The achieve bandwidths at respective frequencies ranges from 10.5 to 28%. The proposed structure is modeled in Computer Simulation Technology microwave studio (CST MWS) and the simulated results are experimentally validated. Due to its reasonably small size and support for multiple wireless standards, the proposed antenna can be used in modern handheld fifth generation (5G) devices as well as Internet of Things (IoT) enabled systems in smart cities.
A MIMO antenna system is designed and presented for sub-6 GHz mobile phone applications. The proposed antenna design consists of six loop-type radiation elements. From the six elements, four elements ...are placed at the corners of the mobile phone PCB by following pattern diversity configuration, while the rest of the two elements are placed in the center of the PCB. Furthermore, a <inline-formula> <tex-math notation="LaTeX">50\Omega </tex-math></inline-formula> coaxial connector is utilized to feed the antenna elements. From the presented results, it is demonstrated that the elements placed at the edges are resonating at 2.5 GHz, and the center placed elements provide resonance at 3.5 GHz. Moreover, according to S 11 ≤ −6 dB, the impedance bandwidth for both the bands is 790 MHz (2.3-3.09 GHz) and 1.18 GHz (2.99-4.17 GHz), respectively; while for S 11 ≤ −10 dB, the impedance bandwidth for both the bands is noted to be 340 MHz (2.38-2.72 GHz) and 650 MHz (3.17-3.84 GHz), respectively. A gain of more than 4 dBi and >85% radiation efficiency are achieved for the single radiation element. The presented antenna design also provides sufficient radiation coverage supporting different sides of the mobile phone PCB. In addition, the effects of the human hand and head on antenna's performance are studied and it was observed that the proposed antenna system provides acceptable properties in the data mode and talk mode.
In this paper, a high-gain THz antenna array is presented. The array uses a polyimide substrate with a thickness of 10 μm, a relative permittivity of 3.5, and an overall volume of 2920 μm × 1055 μm × ...10 μm, which can be employed for THz band space communication and other interesting applications. The dual-band single-element antenna is designed in four steps, while operating at 0.714 and 0.7412 THz with −10 dB bandwidths of 4.71 and 3.13 GHz, providing gain of 5.14 and 5 dB, respectively. In order to achieve a high gain, multiple order antenna arrays are designed such as the 2 × 1 antenna array and the 4 × 1 antenna array, named type B and C, respectively. The gain and directivity of the proposed type C THz antenna array are 12.5 and 11.23 dB, and 12.532 and 11.625 dBi at 0.714 and 0.7412 THz, with 99.76 and 96.6% radiation efficiency, respectively. For justification purposes, the simulations of the type B antenna are carried out in two simulators such as the CST microwave studio (CSTMWS) and the advance design system (ADS), and the performance of the type B antenna is compared with an equivalent circuit model on the bases of return loss, resulting in strong agreement. Furthermore, the parametric analysis for the type C antenna is done on the basis of separation among the radiating elements in the range 513 to 553 μm. A 64 × 1 antenna array is used to achieve possible gains of 23.8 and 24.1 dB, and directivity of 24.2 and 24.5 dBi with good efficiencies of about 91.66 and 90.35% at 0.7085 and 0.75225 THz, respectively, while the 128 × 1 antenna array provides a gain of 26.8 and 27.2 dB, and directivity of 27.2 and 27.7 dBi with good efficiency of 91.66 and 90.35% at 0.7085 and 0.75225 THz, respectively. All the results achieved in this manuscript ensure the proposed design is a feasible candidate for high-speed and free space wireless communication systems.
Introduction Spinal cord injury, due to traumatic or non-traumatic causes, is a medically challenging and life-disrupting condition. The injury disrupts neural signaling and is a medical emergency ...requiring immediate treatment that can reduce long-term effects like paralysis or partial disability of the body. It has costly consequences both for individuals and families because it causes not only physical disability but dependency on others. The main objectives of the study were to determine the frequency of spinal injuries, their nature, and their causes. Materials and methods A descriptive exploratory study was conducted in the neurosurgery wards of two major hospitals of Peshawar, Lady Reading Hospital and Hayatabad Medical Complex. Necessary permission was taken from the administration of both hospitals before starting data collection. The duration of the study was three months, from October to December 2014. A total of 768 patients were retrieved from the ward records for 2013, from which a 50% random sample was taken (384 patients) while incomplete patient records were excluded. The data were transferred and recorded on a pre-constructed proforma covering all the required variables of the study. Finally, the data were transferred to SPSS 15 (SPSS Inc., Chicago) for analysis of descriptive statistics. In addition, comparisons were done by gender, hospitals, types of injuries, and causes of injuries. The chi-square test was used to compare groups for significant differences in frequencies, keeping p ≤0.05 as significant. Results Major factors for spinal cord injury were traumatic and non-traumatic. This study revealed that out of the total patients, 35% faced trauma as a cause of spinal disorder out of which 42%, 29%, and 21% were sudden falls, road traffic accidents (RTAs), and weight lifting, respectively. While non-traumatic causes were 52% mostly due to congenital anomalies (24%), stenosis (23%), and tumor (12%). Levels most commonly involved were lumbar (42.3%) followed by patients involving multiple levels (32.52%), L5-S1 (20.87%), thoracic (2.42%), and cervical (1.92%). Conclusions The traumatic injury was the leading cause of spinal cord injury in the present study where RTAs and falls contributed the most. Congenital abnormalities and spinal cord stenosis were more frequent among non-traumatic spinal cord injuries. The surgical approach was the only way of management practiced for spinal cord injuries in both of the tertiary care hospitals.
Stroke is one of the fatal diseases that affect the brain and causes death within 3 to 10 h. However, most of the deaths caused by a stroke can be avoided with the identification of the nature of ...stroke and react to it in a timely manner by intelligent health systems. The state-of-the-art cyber-physical systems (CPS) enable interaction between physical and computational world to identify any anomaly in the physical world and respond to it. The response of CPS may vary depending upon the context of the physical world. Extensive research has been done in this area from the perspective of wireless sensor networks, body area networks, and wearable smart devices. This paper proposes a CPS for detecting the occurrence of stroke in patients, who have a high risk of stroke or have survived a stroke before. The developed CPS sends recorded data to the doctor and alerts him when the stroke occurs. The proposed system is operating on data acquired from electroencephalography sensors from patients' brain. This article aimed at decreasing human mortality rate due to stroke and will bridge the gaps in CPS due to interdisciplinary isolation. The disciplines involved in the development of a CPS include communication networks, pattern recognition, software engineering, mathematics, and biomedical.
In this work, we present a highly compact multi-branch structure multi-band antenna with a grounded coplanar waveguide (GCPW)-fed structure printed on 26 × 13 × 1.6 mm3 sized FR-4 substrate having ...dielectric constant εr of 4.3 and loss tangent δ of 0.02. In the proposed antenna, five branches are extended from the main radiator to provide multi-band behavior. Two branches are introduced at the upper end of the main radiator, effectively covering the lower bands, while the other three branches are introduced near the center of the main radiator to extend operation to higher bands. The designed antenna covers five different bands: 2.4 GHz, 4.5 GHz, 5.5 GHz, 6.5 GHz, and 7.8 GHz, with respective gain values of 1.34, 1.60, 1.83, 1.80, and 3.50 dBi and respective radiation efficiency values of 90, 88, 84, 75, and 89%. The antenna shows a good impedance bandwidth, ranging from 170 MHz to 3070 MHz. The proposed antenna is simulated in CST Microwave Studio, while its performance is experimentally validated by the fabrication and testing process. The antenna has potential applications for IoT, sub-6 GHz 5G and WLAN (both enablers for IoT), C-band, and X-band services.
Recent advancements in radio frequency (RF) sensing technology can be attributed to the development of the Internet of Things (IoT), healthcare, RF-identification, and communication applications. RF ...sensing is a multidisciplinary research field that requires expertise in computing, electronics, and electromagnetics to cover all system features, including protocol development, antenna design, sensor integration, algorithm formulation, interconnection, data, and analytics. The overarching aim of this work is to present detailed information about RF technologies and their innovations and application diversity from the novel work carried out at CSI Lab
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, together in one platform with an extensive survey. This study presents state-of-the art applications and RF sensing that include W-Fi, radar, and SDR and RFID-based sensing. A comprehensive survey and study of the advantages and limitations of each non-contact technology is discussed. Additionally, open research gaps have been identified as well. Decades of knowledge and experience have been put to use to meet new challenges and demands. The development and study of RF systems, IoT, RFID sensing, and research and deployment activities, are briefly discussed. The emerging research projects with industry, institutional research centers, and academic studies are also addressed. Finally, an outline of identified potential future research areas is provided, emphasizing opportunities and challenges.
The Federal Communication Commission (FCC) has authorized the use of unlicensed ultra-wide band (UWB) spectrum in the frequency range from 3.1 to 10.6 GHz for a variety of short-range applications, ...including wireless monitors and printers, camcorders, radar imaging, and personal area networks (PANS). However, the interference between coexisting narrowband channels and UWB signals that share the same spectrum should be avoided by designing UWB antennas with band notch characteristics. This work presents a printed monopole antenna (PMA) with slots of different shapes etched in the radiating element to obtain band rejection in the three coexisting communication bands, i.e., Worldwide Interoperability for Microwave Access (WiMAX), Wireless Local Area Network (WLAN), and International Telecommunication Union (ITU). A rectangular slot is etched to reject the WiMAX band (3.01-3.68 GHz), an upturned C slot stops the WLAN band (5.18-5.73 GHz) while an inverted-U slot halts the ITU frequency band (7.7-8.5 GHz). The proposed antenna occupies a volume of 32 x 30 x 1.6 mm3 and it radiates efficiently (>90%) with a satisfactory gain (>1.95 dBi) in the unnotched UWB frequency range. The simulations are performed in High Frequency System Simulator (HFSS), while the measurements are conducted in antenna measurement facility and found in close agreement with the former.
In modern communication systems, polarization has always been a major issue. Traditional polarization converters have limited uses because of their enormous size and narrow bandwidth. In this paper, ...an ultra-wideband and high efficient polarization converting metasurface (PCMS) is designed for radar cross section (RCS) reduction. The designed PCMS consists of I-shape unit cell manifesting linearly polarized (LP) incident wave to its orthogonal equivalent. In a frequency range of 10.5 GHz to 29.5 GHz, the design PCM achieves a polarization conversion ratio (PCR) more than 90% with 95% fractional bandwidth (FBW). The designed PCMS is used in a triangular chessboard configuration to reduce the RCS. To obtain destructive interference, the proposed array consists of two-unit cells, PCMS and its mirror, with a phase difference of 180 ± 37°. To reduce RCS, the proposed PCMS unit cell is rotated at 90°, 180°, and 270° for phase cancellation. The proposed array reduced RCS in the ultra-wide frequency range of 8.2 GHz to 29.4 GHz with 113% FBW. The proposed PCMS is validated experimentally. Simulation and experimental results are found in good agreement.
•Highly efficient and ultra-wideband polarization converter which offers both polarization conversion and RCS reduction is designed.•The PCR exceeds 90% in the frequency range of 10.5-29.5 GHz (with a fractional bandwidth of 95%).•It also achieves the RCS reduction of −10 dB in the frequency range of 8.2-29.4 GHz with a FBW of 113%.•It offers high efficiency, ultra-wide bandwidth, simple structure having a minimal thickness then other converters with a single layer in the literature.•It performs the polarization conversion and RCS reduction with its simple structure,low profile and compact structure.
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