63 research outputs found
Laser Prototyping of Low Temperature Co-fired Ceramics for System-In-Package Applications
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Miniaturization of SIW Cavity Filters Through Stub Loading
No full textThis article reports on a simple yet efficient miniaturization technique of substrate integrated waveguide cavity resonators through stub loading. The stubs are attached to the cavity side edges and they are coupled with the magnetic fields of the cavity. This setup allows the stub loaded cavity to operate below its fundamental resonant frequency. This miniaturization technique is demonstrated by developing a two pole filter in horizontally and vertically coupled configurations. The potential to incorporate electronic tuning and various possible applications of these miniaturized cavities in low frequency system-in-package designs make them an excellent choice as compared to their conventional counterparts
A Miniaturized and Polarization Insensitive FSS and CFSS for Dual Band WLAN Applications
No full textThis article reports on a dual band, polarization insensitive Frequency Selective Surface (FSS) for Wi-Fi and WLAN shielding applications. The design incorporates concentric square and circular loops loaded with log periodic directors and passion crosses, respectively. The proposed design is completely polarization insensitive. Also, the design has angular stability up-to 45 for both Transverse Electric (TE) and Transverse Magnetic (TM) polarizations. The FSS offers measured suppression of 38 dB at 2.4 GHz and 32 dB at 5.9 GHz. The detailed analysis of all parameters has been carried out. Equivalent lumped circuit model has also been proposed. The design is highly miniaturized with the unit element size of 0.1 lambda(0) only. The complementary bandpass FSS has also been investigated. The measured results are in good agreement with the simulated response. The design has excellent potential for EM field suppression and security applications. (C) 2019 Elsevier GmbH. All rights reserved
Precipitants of Acute Decompensated Heart Failure and their Correlation with the Severity of Decompensation in a Resource Poor Country
Get PDFObjective: 1. To determine the frequency of various factors (patient related, disease related and physician related), causing immediate precipitation of congestive cardiac failure in a tertiary care hospital. 2. To establish correlation between these variables and severity of decompensated heart failure. Patients and Methods: This cross-sectional study was carried out over a period of March-August, 2016. All patients admitted to cardiology ward and Coronary Care Unit (CCU) of Pakistan Institute of Medical Sciences during the study period were enrolled in the study using consecutive sampling technique. An arbitrarily predetermined sample size of 115 patients was taken. Precipitants were classified as patient related, disease related and physician related. Data was recorded and analyzed using SPSS version 22. Qualitative variables were reported as percentages and quantitative variables by using mean ± standard deviation. Spearman correlation coefficient was used to determine the correlation between variables and outcome measures. Results: A total of 115 patients were enrolled in this study. The mean age of the population was 51.13±13.6 years. Among these 38.3% of the population was obese. The patients remained admitted to the hospital for the index episode of decompensation for a mean period of 4.14±1.2 days. Infections were found to be the leading precipitant contributing to 57.6% of all decompensation episodes. This was followed by drug non-compliance (17.4%) and arrhythmias (8.7%). Ischemia was noted in 5.2%. Heart failure severity at presentation was found to correlate significantly with the presence of hypertension (Spearman coefficient 0.62, p-value 0.04), baseline hemoglobin (Spearman coefficient -0.58, p-value 0.03), creatinine levels (Spearman coefficient 0.71, p-value 0.05) and precipitant of heart failure (Spearman coefficient 0.257, p-value 0.007). Conclusion: A sizeable majority of heart failure hospitalizations can be prevented by inculcating measures directed at effective infection control at community and health care level and educating patients regarding recognition of early signs of infection that may target the most important immediate precipitant for acute decompensated heart failure.  
A compact band-stop frequency selective surface for dual band Wi-Fi applications
No full textThis article presents a compact frequency selective surface (FSS) design which is capable of rejecting both bands of Wi-Fi. The proposed design is evolved from a patch-slot topology and it is investigated that the patch-slot architecture is unstable for oblique incident waves, therefore, a number of geometrical modifications have been proposed to ensure the band stability at different incident angles. The slot geometry is modified by inductive loading and extending the slot length. The modified unit element of FSS is 0.38 0at higher frequency band. Fabricated prototypes have been measured for their transmission response at incident angles upto 30 and good agreement has been observed between simulated and measured results. The proposed FSS is suitable for shielding applications and for limiting the coverage area of wireless access-point
Efficient Design Methodology for a Complex DRA-SIW Filter-Antenna Subsystem
No full textThis work reports on an efficient design methodology for realizing hybrid filter-antenna subsystems. Designing a filter-antenna subsystem in the case of complex multimode filter is not straightforward. The coupling of the antenna with a multimode filter depends upon several uncorrelated parameters. An efficient design methodology is proposed which can address these complex problems. The work focuses on the characterization of radiating and filtering elements and then proposes a reliable model, which is derived mathematically as well as from rigorous statistical analyses, which can then be used for designing hybrid filter-antenna structures such as a hybrid DRA codesigned with a SIW based multimode filter. A highly compact filter-antenna subsystem has been designed employing the proposed methodology, and the measured results validate the proposed design technique.</p
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