Effects of a Smaller Unit Cell Planar EBG Structure on the Mutual Coupling of a Printed Dipole Array

A new smaller unit-cell planar electromagnetic bandgap (EBG) structure is proposed on low dielectric constant low-cost substrate (TMM: epsilon(r) = 4.5, thickness = 25 mils) that has a stopband frequency at around 4 GHz. The proposed structure when placed in between a two-element printed dipole array results in over 13-dB reduction in mutual coupling and a significant improvement in antenna return loss bandwidth and gain pattern

Wideband Smaller Unit-Cell Planar EBG Structures and Their Application

A new low-cost smaller unit-cell planar electromagnetic bandgap (ERG) structure operating at the lower GHz frequencies (below 6 GHz) is proposed. ERG structures based on this new geometry are designed on a number of commonly available substrates. Characteristics of such structures, such as bandgap and reflection phase profile are analyzed. a simple empirical model is proposed to predict the surface wave stopband frequency of the proposed ERG structure. Finally, a low-profile dipole antenna is designed and tested for operation on the ERG structure

Effects of EBG Reflection Phase Profiles on the Input Impedance and Bandwidth of Ultrathin Directional Dipoles

A comprehensive study of the effects of the reflection phase profiles on dipole antennas is presented with the ultimate objective of designing ultrathin printed dipoles (as thin as one hundredth of the wavelength). Dipole driving-point impedance and bandwidth are studied as function of various electromagnetic bandgap (EBG) reflection phase profiles. It is demonstrated that although many different reflection phase profiles can be generated for a certain antenna height, it is the profile that satisfies a specific range of reflection phase angles that is required to achieve good antenna performance. Such optimum EBG phase profiles are generated for a number of antenna heights and their influence on a dipole antenna impedance and bandwidth are also studied. Finally, an actual EBG structure and a printed dipole antenna are designed, fabricated and tested. The overall antenna height for this case was 0.03 lambda. The computed and measured results show that efficient printed dipoles on ultrathin grounded dielectric substrates can be developed that will substantially reduce the sizes and weight of large arrays

Investigation on Physico-Chemical Properties of 100% Cotton Woven Fabric Treated with Titanium Dioxide

<p>This paper represents an approach to observe the physic-chemical effects of titanium dioxide (TiO2) applied on 100% cotton woven fabric. Cotton fabric was treated with TiO2 by exhaustion method and followed by necessary curing and washing processes. The treated fabrics were then analyzed by Scanning Electron Microscope (SEM) and the tensile strength, pH and absorbency of the treated and untreated fabrics were examined. It was found that titanium dioxide impairs the hand feel and absorbency of 100% cotton woven fabrics, wetting time of all treated fabrics increased gradually than untreated fabrics. The treatment increases the tensile strength of 100% cotton woven fabrics. The treatment with titanium dioxide also kept the pH of the fabric in acidic medium.</p

SARS-CoV-2 vaccination modelling for safe surgery to save lives: data from an international prospective cohort study

Background: Preoperative SARS-CoV-2 vaccination could support safer elective surgery. Vaccine numbers are limited so this study aimed to inform their prioritization by modelling. Methods: The primary outcome was the number needed to vaccinate (NNV) to prevent one COVID-19-related death in 1 year. NNVs were based on postoperative SARS-CoV-2 rates and mortality in an international cohort study (surgical patients), and community SARS-CoV-2 incidence and case fatality data (general population). NNV estimates were stratified by age (18-49, 50-69, 70 or more years) and type of surgery. Best- and worst-case scenarios were used to describe uncertainty. Results: NNVs were more favourable in surgical patients than the general population. The most favourable NNVs were in patients aged 70 years or more needing cancer surgery (351; best case 196, worst case 816) or non-cancer surgery (733; best case 407, worst case 1664). Both exceeded the NNV in the general population (1840; best case 1196, worst case 3066). NNVs for surgical patients remained favourable at a range of SARS-CoV-2 incidence rates in sensitivity analysis modelling. Globally, prioritizing preoperative vaccination of patients needing elective surgery ahead of the general population could prevent an additional 58 687 (best case 115 007, worst case 20 177) COVID-19-related deaths in 1 year. Conclusion: As global roll out of SARS-CoV-2 vaccination proceeds, patients needing elective surgery should be prioritized ahead of the general population