Novel wire grid embedded C-sandwich radome structures for broadband airborne applications

The application of symmetric wire grid structures for the broadbanding of C-sandwich radome panel, with core thickness optimized for power transmission, is presented. The performance parameters of wire grid embedded C-sandwich wall are evaluated based on equivalent transmission line method. The superior broadband EM performance of wire compensated C-sandwich wall is established based on a comparative study with the conventional structure at normal incidence and at a high incidence angle often encountered in streamlined airborne radomes

A Review of Metamaterial Invisibility Cloaks

The exciting features of metamaterial in conjunction with transformation optics leads to various applications in the microwave regime with such examples as invisible cloak, frequency selective surfaces (FSS), radomes, etc. The concept of electromagnetic invisibility is very much important in aerospace platform. Hence to study the feasibility of implementation of this concept for stealth, an extensive literature survey of metamaterial cloaks has been carried out and reported in this paper along with the basic concept of cloaking. To make the review more effective, the technical papers are classified into three broad sections viz. mathematical modeling, design and simulations, and fabrications and experimental demonstration. Further the design and simulation is focused on different techniques implemented such as finite difference time domain (FDTD), finite element method (FEM), finite integration technique (FIT), inductor-capacitor representation of metamaterial (LC MTM) etc. The review also reports the methods implemented for analysis of metamaterial cloaks with possibility of application to the specific frequency rang

Bacteria Foraging Algorithm for Metamaterial Design and Optimization

Soft computing techniques are emerging as highly efficient global optimization techniques in the field of electromagnetics. These techniques along with the EM software have proved their efficiency in antenna engineering, wireless communication, absorber design and a few in the field of metamaterial structural analysis. Bacteria foraging algorithm, although has been used recently in controls, is still new to the field of metamaterial science and technology. In this paper, bacteria foraging algorithm (BFA) is used for design optimization of a double ring circular split ring resonator. Equivalent circuit analysis is used the EM tool for analysis of the CSRR. The aim of bacteria foraging algorithm is the estimation of structural parameters of the CSRR at a desired frequency range. Further the developed algorithm is proved through extraction of parameters of the optimized metamaterial structure. A comparative study with other soft computing techniques w.r.t. accuracy and computational time is provided

Analytical Estimation of Radar Cross Section of Dipole Array with Parallel Feed

The scattering characteristics of a phased array depends on its design parameters including its feed. In this paper, the radar cross section of dipole array with parallel-feed network is calculated. The scattered field is obtained by in terms of reflection and transmission coefficients at each component level of the array system. The mutual coupling effect is considered. Scattering till second level of couplers in feed network is taken into account. The analysis presented can be useful in low RCS phased array design

Electromagnetic Design of a Hybrid Variable Thickness Airborne Radome

Abstract attached as PD

EM Performance Analysis of Tri-layer Metamaterial FSS for Radome Applications

Abstract attached as PD

Radar Cross Section (RCS) of a Series-Fed Dipole Array including Mutual Coupling Effect

Abstract attached as PD

A Study of Dolph-Chebyshev Spherical Phased Antenna Array for Wave Propagation and Aerospace Applications

Abstract attached as PD

Prolapse or incontinence: what affects sexual function the most?

Introduction and hypothesis Pelvic organ prolapse (POP) and stress urinary incontinence (SUI) adversely affect sexual function in women. Comparative studies of the two subgroups are few and results are conflicting. The aim of this study was to compare the effect of POP and SUI on the sexual function of women undergoing surgery for these conditions. Methods The study population comprised women with POP or SUI in a tertiary referral hospital in the UK. Women who underwent SUI surgery had no symptoms of POP and had urodynamically proven stress incontinence. Patients with POP had ≥ stage 2 prolapse, without bothersome urinary symptoms. Pre-operative data on sexual function were collected and compared using an electronic pelvic floor assessment questionnaire (ePAQ). The incidence of sexual dysfunction and comparison of symptoms in both groups were calculated using the Mann–Whitney U test. Results Three hundred and forty-three women undergoing surgery for either SUI or POP were included. Patients were age-matched, with 184 undergoing SUI surgery (age range 33–77 years) and 159 POP surgery (age range 27–78 years; p = 0.869). The overall impact of POP and SUI was not significantly different in the two subgroups (p = 0.703). However, both patients (73 % vs 36 %; p = 0.00) and partners (50 % vs 24 %; p = 0.00) avoid intercourse significantly more frequently in cases with POP compared with SUI. This did not have a significant impact on quality of life. Conclusions The impact of bothersome SUI or POP on sexual function was found to be similar, but patient and partner avoidance in women with POP was greater than those with SUI

Distinct Patterns of Brain Metabolism in Patients at Risk of Sudden Unexpected Death in Epilepsy

Objective: To characterize regional brain metabolic differences in patients at high risk of sudden unexpected death in epilepsy (SUDEP), using fluorine-18-fluorodeoxyglucose positron emission tomography (18FDG-PET). Methods: We studied patients with refractory focal epilepsy at high (n = 56) and low (n = 69) risk of SUDEP who underwent interictal 18FDG-PET as part of their pre-surgical evaluation. Binary SUDEP risk was ascertained by thresholding frequency of focal to bilateral tonic-clonic seizures (FBTCS). A whole brain analysis was employed to explore regional differences in interictal metabolic patterns. We contrasted these findings with regional brain metabolism more directly related to frequency of FBTCS. Results: Regions associated with cardiorespiratory and somatomotor regulation differed in interictal metabolism. In patients at relatively high risk of SUDEP, fluorodeoxyglucose (FDG) uptake was increased in the basal ganglia, ventral diencephalon, midbrain, pons, and deep cerebellar nuclei; uptake was decreased in the left planum temporale. These patterns were distinct from the effect of FBTCS frequency, where increasing frequency was associated with decreased uptake in bilateral medial superior frontal gyri, extending into the left dorsal anterior cingulate cortex. Significance: Regions critical to cardiorespiratory and somatomotor regulation and to recovery from vital challenges show altered interictal metabolic activity in patients with frequent FBTCS considered to be at relatively high-risk of SUDEP, and shed light on the processes that may predispose patients to SUDEP