This research work proposes a compact four-port multiple-input multiple-output (MIMO) antenna that operates in the whole license free ultra-wideband (UWB) spectrum of 3.1–10.6 GHz. Spatial diversity has been introduced by arranging these antennas in close proximity without developing a strong mutual coupling. Antenna elements are evolved from a conventional rectangular patch antenna whereas a customized decoupling structure is introduced on the back side of the substrate to achieve the desired isolation level. The parasitic decoupling structure consists of different features which are resonant at different frequencies offering a whole UWB coverage. In addition to the decoupling structure a dumbbell shaped stub has also been introduced to the partial ground plane to suppress the mutual coupling. The overall measured isolation among elements is more than 20 dB. Different MIMO performance parameters have also been investigated from the measured results. Whole MIMO system measures 0.41 λo × 0.44 λo at 3.1 GHz. The MIMO system is intended for high data rate and short-range communication devices used in wireless personal area networks.
Renalase is considered as a novel candidate gene for type 2 diabetes. In this study, we aimed to investigate the relationship of serum renalase and two single nucleotide polymorphisms with gestational diabetes mellitus. One hundred and ninety-eight normotensive pregnant females (n = 99 gestational diabetes mellitus; n = 99 euglycemic pregnant controls) were classified according to the International Association of the Diabetes and Pregnancy Study criteria. Fasting and 2-h post glucose load blood levels and anthropometric assessment was performed. Serum renalase was measured using enzyme-linked immunosorbent assay, whereas DNA samples were genotyped for renalase single nucleotide polymorphisms rs2576178 and rs10887800 using Polymerase chain reaction-Restriction fragment length polymorphism method. In an age-matched case control study, no difference was observed in the serum levels of renalase (p > 0.05). The variant rs10887800 showed an association with gestational diabetes mellitus and remained significant after multiple adjustments (p < 0.05), whereas rs2576178 showed weak association (p = 0.030) that was lost after multiple adjustments (p = 0.09). We inferred a modest association of the rs10887800 polymorphism with gestational diabetes. Although gestational diabetes mellitus is self-reversible, yet presence of this minor G allele might predispose to metabolic syndrome phenotypes in near the future.
A miniaturized frequency selective surface (FSS) based electromagnetic shield having wide band response is presented in this paper. A novel square FSS (SFSS) is designed and optimized over a single-layer dielectric and achieves electromagnetic shielding for SATCOM in X-band. This SFSS also achieves a stable frequency response at normal and oblique angles of incidences in both TE and TM wave modes. Simulated and measured results verify shielding effectiveness of the proposed FSS over a wide band. K E Y W O R D S band-stop response, electromagnetic interference (EMI), electromagnetic shielding, frequency selective surface (FSS), polarization independent
This paper presents a compact single layer reflectarray antenna based on a diagonally notched square patch and a pair of circular delay-lines, for X-band applications. The length and width of circular delay-lines are varied and optimized to attain a linear phase range of more than 600º. The effect of incident angle in TE and TM modes at 0º, 15º and 30º is studied, which offers stable angular phase range. The hybrid Finite Element Boundary Integral (FEBI) method is used for simulation of the whole reflectarray system comprising of 27 × 27 elements and being fabricated on a low cost FR-4 laminate. The measured gain of 24.5 dBi with aperture efficiency of 49.5% is achieved at 10 GHz. The proposed design provides the measured 1-dB gain bandwidth of 12.5% and 3-dB gain bandwidth of 34%. The simulated and measured side-lobe-levels and cross polarizations are less than-25 dB and-40 dB, respectively.
In this article, a high‐gain antenna for ultra‐wideband (UWB) communication is presented and experimentally validated. Gain enhancement is achieved by employing a frequency selective surface (FSS) screen as a superstrate. The proposed antenna‐FSS arrangement is less complex and realized on a low‐profile FR‐4 laminate. The antenna comprises a circular radiator that is enclosed in a triangular shaped arrangement of slots along with a narrow feed‐line. Lengths and widths of the different sections along with feed are optimized to achieve an ultra‐wide impedance bandwidth. The employed superstrate is an array of modified square shaped FSS (MS‐FSS). Full wave analysis validates its effectiveness in achieving at least 5 dBi gain enhancement of the UWB antenna while maintaining wideband impedance match. Moreover, the antenna behavior is also analyzed by varying periodicity and the distance between superstrate and the proposed slot antenna. This antenna‐FSS arrangement is a suitable candidate for high‐gain UWB portable devices.
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