For high speed downlinking of payload data from small satellites, a new 4×4 aperture coupled microstrip patch array antenna has been presented. The antenna is designed for the Ku band and a peak gain of 18.0 dBi is achieved within the impedance bandwidth from 11.75 GHz to 12.75 GHz. Wide bandwidth is achieved as the patch elements are excited through E-shaped slots having asymmetric side lengths and widths. Each square patch element of the array with truncated corners and appropriately placed slots generates right hand circularly polarized (RHCP) radiation with very high crosspolarization discrimination. A corporate feed network consisting of T-junctions and quarter-wave impedance transformers is developed to feed the array elements from a single coaxial port of 50 Ω. To improve the radiation from the patches and waveguiding in the feed network, two types of Rogers substrates with different dielectric constant and thickness are considered. Our proposed microstrip patch array antenna of size 7.8 cm × 6.4 cm × 0.3 cm can perform efficiently with a downlink data rate as high as 4.6 Gbps for small satellites.

An intelligent security model for the big data environment is presented in this paper. The proposed security framework is data sensitive in nature and the level of security offered is defined on the basis of the data secrecy standard. The application area preferred in this work is the healthcare sector where the amount of data generated through the digitization and aggregation of medical equipment’s readings and reports is huge. The handling and processing of this great amount of data has posed a serious challenge to the researchers. The analytical outcomes of the study of this data are further used for the advancement of the medical prognostics and diagnostics. Security and privacy of this data is also a very important aspect in healthcare sector and has been incorporated in the healthcare act of many countries. However, the security level implemented conventionally is of same level to the complete data which not a smart strategy considering the varying level of sensitivity of data. It is inefficient for the data of high sensitivity and redundant for the data of low sensitivity. An intelligent data sensitive security framework is therefore proposed in this paper which provides the security level best suited for the data of given sensitivity. Fuzzy logic decision making technique is used in this work to determine the security level for a respective sensitivity level. Various patient attributes are used to take the intelligent decision about the security level through fuzzy inference system. The effectiveness and the efficacy of the proposed work is verified through the experimental study.

A quasi-Yagi microstrip patch antenna with four directors and truncated ground plane has been designed and fabricated to have an ultra-wide bandwidth, high gain, low return loss and better directivity with center frequency at 3.40 GHz. After optimization, the proposed antenna yields an ultra-wide bandwidth of 1.20 GHz with lower and upper cutoff frequencies at 3.12 GHz and 4.32 GHz, respectively. High gain of 5.25 dB, return loss of -28 dB and directivity of 6.28 dB are obtained at resonance frequency of 3.40 GHz. The measured results of fabricated antenna have shown excellent agreement with the simulation results providing bandwidth of 1.34 GHz with lower and upper cutoff frequencies at 3.04 GHz and 4.38 GHz, respectively. The antenna gain of 5.33 dB, return loss of -44 dB are obtained at resonance frequency of 3.36 GHz. The dimension of the antenna is only of 65 mm x 45 mm ensuring compact in size.