A High-Performance, Low-Cost, and Integrated Hairpin Topology RF Switched Filter Bank for Radar Applications.

Switched filter banks find widespread application in frequency-hopping radar systems and communication networks with multiple operating frequencies, especially in situations demanding elevated filter element isolation. In this paper, the design and implementation of a highly isolated switchable narrow-bandpass filter bank architecture using hairpin microstrip topology is presented. The filter bank has four discrete bandpass filters with passbands of 2.0-2.2 GHz, 2.3-2.5 GHz, 3.1-3.3 GHz, and 3.9-4.1 GHz. These filters span the radar S-frequency band (2.0-4.0 GHz). In order to switch between channels with a switching speed of nanoseconds, low-loss and highly isolated SP4T switches are implemented. Advanced design system (ADS) software is used to design the various filter functionalities, and the entire system is tested on a vector network analyzer (VNA). The proposed architecture makes it much easier to put the filter bank into practice and switch it to the desired frequency, which is useful for radar receiver applications.

Miniaturized Broadband Bi-Yagi Antenna Array for Ambient RF Energy Harvesting.

This paper presents a miniaturized broadband Bi-Yagi antenna array that covers a bandwidth from 1.79 GHz to 2.56 GHz. The proposed antenna achieves a tradeoff between maximizing bandwidth, effective area, and gain while minimizing physical dimensions. The antenna design considers the coupling between the radiator and director elements, resulting in increased bandwidth as the resonating modes shift apart. Additionally, the proposed design optimizes element spacing and dimensions to achieve high gain, wide bandwidth, efficient radiation, and a minimum aperture size. The proposed antenna, with physical dimensions of 138.6 mm × 47.7 mm × 1.57 mm, demonstrates gains ranging from 6.2 dBi to 9.34 dBi across the frequency range, with a total efficiency between 88% and 98%. The proposed design is experimentally validated by measuring the reflection coefficients, input impedance, gain, and normalized radiation pattern. These features make the antenna well suited for capturing and harvesting electromagnetic waves in mobile wireless and Wi-Fi applications.

Design and optimization of a transparent and flexible MIMO antenna for compact IoT and 5G applications.

This work presents an optically transparent and flexible MIMO antenna that features two square patch elements placed in close proximity, aiming to meet the demands of compactness, flexibility, optical transparency, and visual appeal for IoT applications and future 5G wireless communication. The design includes a simple offset fed configuration to achieve the required isolation and impedance matching. It simplifies the process of creating closely spaced transparent MIMO antenna configurations. By optimizing and analyzing this structure, the antenna achieves better isolation and diversity gain performance, even when the patch elements are positioned very close to each other. To achieve optical transparency and flexibility, the antenna uses thin polyethylene terephthalate (PET) material as a substrate, which is a thermoplastic polymer resin from the polyester family. The wired metal mesh parameters for conducting parts of the MIMO antenna and offset position of the feed are carefully optimized to achieve required optical transparency, isolation, impedance matching and radiation performance without any complex decoupling or impedance matching network.

Dual-sense slot-based CP MIMO antenna with polarization bandwidth reconfigurability.

In this letter, a compact, planar circularly polarized (CP) sub-GHz slot-based multiple-input-multiple-output (MIMO) antenna with dual sense CP along with polarization bandwidth reconfigurability is presented. The pentagonal reactively loaded slot is fed by two folded tapered feedlines to achieve CP. The antenna offers left-hand-circular polarization (RHCP) with the as well as right hand circular polarization (LHCP). The antenna exhibit linearly polarization (LP) by exciting two ports simultaneously. Moreover, the antenna CP resonance can be reconfigured by varying the capacitance of the varactor diode. The antenna has a wide -10 dB operating frequency band from 578-929 MHz. while the axial ratio (AR) bandwidth ranges from 490-810 MHz. Moreover, the two elements MIMO are optimized and placed on compact dimensions 100 × 100 × 0.76 mm3 to realize pattern diversity. The antenna's key characteristics are compact size, wide-band sub-GHz operation, dual sense CP, polarization bandwidth reconfigurability and good MIMO performance. Thus, it is a suitable candidate to be utilized in CubeSats applications in sub-GHz bands.

A High-Performance Circularly Polarized and Harmonic Rejection Rectenna for Electromagnetic Energy Harvesting.

This paper presents a novel circularly polarized rectenna designed for efficient electromagnetic energy harvesting at the 2.45 GHz ISM band. A compact antenna structure is designed to achieve high performance in terms of radiation efficiency, axial ratio, directivity, effective area, and harmonic rejection over the entire bandwidth of the ISM frequency band. The optimized rectifier circuit enhances the RF harvested energy efficiency, with an AC-to-DC conversion efficiency ranging from 36% to 70% for low-level input power ranging from -10 dBm to 0 dBm. The stable output of DC power confirms the suitability of this design for various practical applications, including wireless sensor networks, energy harvesting power supplies, medical implants, and environmental monitoring systems. Experimental validation, which includes both the reflection coefficient and radiation patterns of the designed antenna, confirms the accuracy of the simulation. The study found that the proposed energy harvesting system has a high total efficiency ranging from 53% to 63% and is well-suited for low-power energy harvesting (0 dBm) from ambient electromagnetic radiation. The proposed circularly polarized rectenna is a competitive option for efficient electromagnetic energy harvesting, both as a standalone unit and in an array, due to its high performance, feasibility, and versatility in meeting various energy harvesting requirements. This makes it a promising and cost-effective solution for various wireless communication applications, offering great potential for efficient energy harvesting from ambient electromagnetic radiation.

Low-Profile Antenna System for Cognitive Radio in IoST CubeSat Applications.

Since the CubeSats have become inherently used for the Internet of space things (IoST) applications, the limited spectral band at the ultra-high frequency (UHF) and very high frequency should be efficiently utilized to be sufficient for different applications of CubeSats. Therefore, cognitive radio (CR) has been used as an enabling technology for efficient, dynamic, and flexible spectrum utilization. So, this paper proposes a low-profile antenna for cognitive radio in IoST CubeSat applications at the UHF band. The proposed antenna comprises a circularly polarized wideband (WB) semi-hexagonal slot and two narrowband (NB) frequency reconfigurable loop slots integrated into a single-layer substrate. The semi-hexagonal-shaped slot antenna is excited by two orthogonal +/-45° tapered feed lines and loaded by a capacitor in order to achieve left/right-handed circular polarization in wide bandwidth from 0.57 GHz to 0.95 GHz. In addition, two NB frequency reconfigurable slot loop-based antennas are tuned over a wide frequency band from 0.6 GHz to 1.05 GH. The antenna tuning is achieved based on a varactor diode integrated into the slot loop antenna. The two NB antennas are designed as meander loops to miniaturize the physical length and point in different directions to achieve pattern diversity. The antenna design is fabricated on FR-4 substrate, and measured results have verified the simulated results.

A High Performance All-Textile Wearable Antenna for Wristband Application.

A compact, conformal, all-textile wearable antenna is proposed in this paper for the 2.45 GHz ISM (Industrial, Scientific and Medical) band. The integrated design consists of a monopole radiator backed by a 2 × 1 Electromagnetic Band Gap (EBG) array, resulting in a small form factor suitable for wristband applications. An EBG unit cell is optimized to work in the desired operating band, the results of which are further explored to achieve bandwidth maximization via floating EBG ground. A monopole radiator is made to work in association with the EBG layer to produce the resonance in the ISM band with plausible radiation characteristics. The fabricated design is tested for free space performance analysis and subjected to human body loading. The proposed antenna design achieves bandwidth of 2.39 GHz to 2.54 GHz with a compact footprint of 35.4 × 82.4 mm2. The experimental investigations reveal that the reported design adequately retains its performance while operating in close proximity to human beings. The presented Specific Absorption Rate (SAR) analysis reveals 0.297 W/kg calculated at 0.5 W input power, which certifies that the proposed antenna is safe for use in wearable devices.

Miniaturized Folded-Slot CubeSat MIMO Antenna Design with Pattern Diversity.

In this paper, a folded slot-based multiple-input-multiple-output (MIMO) antenna design for Cube Satellite (CubeSat) applications is presented for the ultra-high frequency (UHF) band. A unique combination of a reactively loaded meandered slot with a folded structure is presented to achieve the antenna's miniaturization. The proposed antenna is able to operate over a wide frequency band from 430~510 MHz. Moreover, pattern diversity is achieved by the antenna's element placement, resulting in good MIMO diversity performance. The four elements are placed on one Unit (1U) for CubeSat dimensions of 100 mm × 100 mm × 100 mm. The miniaturized antenna design with pattern diversity over a wide operating band is well suited for small satellite applications, particularly CubeSats in the UHF band.

Electromagnetic surface waves supported by a resistive metasurface-covered metamaterial structure.

This study examines the analytical and numerical solution of electromagnetic surface waves supported by a resistive metasurface-covered grounded metamaterial structure. To simulate the metamaterial, the Kramers-Kronig relation based on the causality principle is used, while the modeling of the resistive metasurface has been done by implementing the impedance boundary conditions. The analytical expressions for the field phasors of surface waves are developed for the transverse magnetic (TM) polarized mode and transverse electric (TE) polarized mode. The characteristic equations are computed for both modes, and the unknown propagation constant is evaluated numerically in the kernel. After computation, the dispersion curves, electric field profiles, effective mode index ([Formula: see text]), and phase speeds ([Formula: see text]) are presented for both the TM and TE polarized modes. To study the tunability of surface waves, the influence of the thickness of the metamaterial slab ([Formula: see text]), effective permittivity of the metamaterial ([Formula: see text]), thickness of the resistive metasurface ([Formula: see text]), and effective permittivity of the metasurface ([Formula: see text]) on all the numerical results has been studied. However, the geometrical parameters are found to be more sensitive to the effective mode index ([Formula: see text]) and phase speed ([Formula: see text]) of the surface waves. The results are consistent with the published results, which reflects the accuracy of the work. It is concluded that the appropriate choice of parameters can be used to achieve surface waves with the desired characteristics in the GHz range. The present work may have potential applications in surface waveguide design, surface wave speed controllers, surface communication devices, and light trapping configurations.

Levels of Practice and Determinants of Diabetes Self-Care in Primary Health Care in Jeddah City, Saudi Arabia.

Objective To assess the level and determinants of practice in diabetes self-management at primary health care centers (PHCCs) and to analyze the association of self-management with the level of glycemic control. Method A cross-sectional study was conducted among patients with type 1 and type 2 diabetes, aged ≥ 17 years, and being followed at PHCCs in Jeddah, Saudi Arabia, from December 1, 2019, to December 30, 2019. A multistage cluster sampling technique was used to select 350 participants from five PHCCs. The level of practice in self-management was assessed using the Arabic version of the Summary of Diabetes Self-care Activities (SDSCA) questionnaire. The tool was administered as a face-to-face interview, followed by the collection of sociodemographic and relevant clinical data. In addition, blood was collected to measure fasting blood glucose (FBG) and HbA1c levels. The association of the overall SDSCA score with diabetes control was analyzed using linear regression and the receiver operator characteristics (ROC) curve. Multivariate binary logistic regression was carried out to analyze independent factors of inadequate practice. Result The overall mean (SD) SDSCA score was 3.13 (1.13)/7. Of the five dimensions of self-care, medication adherence yielded the highest score (mean=5.39 days per week), followed by diet (2.83) and blood glucose monitoring (2.78), while footcare had the lowest level of practice (2.26). The SDSCA score showed a negative correlation with the level of HbA1c, with a correlation coefficient r-squared =0.530 and regression coefficient B=-0.648 (p <0.001). ROC curve analysis showed that optimal glycemic control was associated with SDSCA score cutoff ≥3.5 with 82.0% sensitivity and 77.0% specificity, and the model showed that 38.0% of participants had adequate practice in self-management. Inadequate practice in diabetes self-management was independently associated with age >50 years (OR=2.00 [95%CI=1.02, 3.89]), rental accommodation (OR=0.42 [95%CI=0.23, 0.76]), independent job (OR=3.98 [95%CI=1.66, 9.57]), and longer duration of diabetes (≥8 years) (OR=4.25 [95%CI=1.82, 9.92]). Conclusion There are low levels of diabetes self-management among patients being followed at Jeddah PHCCs. This is associated with suboptimal glycemic control among the majority of the patients, indicating the importance of self-management to improve diabetes control. Patient health literacy and education for self-management should be considered the standard of care for diabetic patients in all PHCCs, with specific attention to subcategories of patients with the lowest levels of practice in self-management such as those with a longer duration of diabetes and the elderly.

Drug poisoning and associated factors in western Saudi Arabia: A five-year retrospective chart review (2011-2016).

OBJECTIVE: Drug poisoning is a globally common cause of emergency-room admissions. This study explores drug-poisoning prevalence patterns, associated risk factors (gender, age and exposure circumstances), and outcomes in western Saudi Arabia. METHODS: Retrospective analysis of Clinical drug poisoning cases (2011-2016). The data were retrieved from the Saudi Ministry of Health's record and Patients' medical charts were analyzed. RESULTS: The Ministry of Health received 1,474 reports of drug poisoning during 2011-2016. More than half involved females (n=885, 60%) or young children (0-4 years old) (n=764, 51.8%) and occurred accidentally (n=786, 53.3%); almost all had an oral route of poisoning (n=1,466, 99.5%). The cases most frequently involved analgesic and non-steroidal anti-inflammatory drugs (n=373, 25.2%); antiepileptic, antipsychotic, psychoactive, and anxiolytic drugs (n=229, 16.3%); antihistamine, asthma, flu, and cough drugs (n=157, 12.0%); and antibiotic, anti-fungal; and antiprotozoal drugs (n=74, 5.0%). Antidotes were administered in only 2.2% of cases, and no deaths were reported. CONCLUSION: The drug poisoning cases involved females and young children (younger than 5 years old) and the most cases were accidental, and the most commonly used drugs were analgesics (Panadol), followed by antipsychotics, antihistamines, and antiepileptics (Tegretol).