Helix Inspired 28 GHz Broadband Antenna with End-Fire Radiation Pattern

This paper presents the design and characterization of a via free planar single turn helix for 28 GHz broadband applications.The proposed antenna is designed using ROGERS RO4003 material,having a simple structure and end-fire radiation pattern.The antenna comprises of a compact dimension of 1.36λ_(0)×0.9λ_(0) with a thickness of 0.0189λ_(0)(whereλ_(0) is the free-space wavelength at the central frequency of 28 GHz).Parametric study has been carried out to investigate the impact of key design parameters and to achieve an optimum design.Results show a good agreement between the simulated and measured results.A single turn helical inspired antenna covers−10 dB impedance bandwidth of 26.25-30.14 GHz having a peak gain of 5.83 dB and radiation efficiency up to 85%.Moreover,linear array configurations with 2 and 4 elements have been analyzed for applications with higher gain and space constraints.Presented array configurations are suitable for applications having space constraints in one dimension.Results show that peak gain up to 8.2 dB and 11.1 dB can be achieved with 2 and 4 elements,respectively.Due to its simple planar and via free structure,this antenna is suitable for 5G communications and for sensing,imaging,IoT and tracking applications at 28 GHz band spectrum.

Measuring Tail Dependence for Aggregate Collateral Losses Using Bivariate Compound Shot-Noise Cox Process

In this paper, we introduce tail dependene measures for collateral losses from catastrophic events. To calculate these measures, we use bivariate compound process where a Cox process with shot noise intensity is used to count collateral losses. A homogeneous Poisson process is also examined as its counterpart for the case where the catastrophic loss frequency rate is deterministic. Joint Laplace transform of the distribution of the aggregate collateral losses is derived and joint Fast Fourier transform is used to obtain the joint distributions of aggregate collateral losses. For numerical illustrations, a member of Farlie-Gumbel-Morgenstern copula with exponential margins is used. The figures of the joint distributions of collateral losses, their contours and numerical calculations of risk measures are also provided.

Ultra-wideband Frequency Selective Surface for Communication Applications

A low-profile ultra-wideband(UWB)band-stop frequency selective surface(FSS)is designed for S-,C-,X-and Ku-bands communication applications.The FSS is constructed by using square and circular loop elements printed on the top and bottom sides of the RO3210 substrate.The FSS has been designed to reduce the electromagnetic interference(EMI)as well as to mitigate the harmful effects of electromagnetic radiation on the human body caused by different radio devices.The dimension and size of the UWB FSS have been reduced to 0.12λ×0.12λand 90%,respectively,as compared to the reported literature.The other advantages of the proposed FSS are that it is low profile,it has a simplified geometry and it ensures better angular and polarization stability of up to 85◦.The-10 and-20 dB bandwidths of the proposed FSS are 146%(2.0-13.0 GHz)and 80%(4.87-11.42 GHz),respectively.Theoretical results have been obtained using ANSYS HFSS and verified through measured results.