<p class="MsoNormal" style="margin: 0cm 0cm 0pt; layout-grid-mode: char;"><span style="layout-grid-mode: line; font-family: ";Arial";,";sans-serif";; mso-bidi-font-weight: bold;"><span style="font-size: x-small;">Free Space Optics (FSO) is now a well established access technology, better known for its robustness in transmitting large data volumes in an energy efficient manner. However the BER performance of a FSO ground-link is adversely affected by cloud coverage, harsh weather conditions, and atmospheric turbulence. Fog, clouds and dry snow play a detrimental role by attenuating optical energy transmitted in terrestrial free-space and thus decrease the link availability and reliability. We measured the time variation of received optical signal level during continental fog and dry snowfall over a link distance of 80 m. We perform a detailed analysis of the continental fog and dry snow attenuation results and further characterise them by presenting some useful attenuation statistics and also showing their comparison with the corresponding measured density values collected by a particle sensor device. We propose also an empirical relationship between temperature, relative humidity and optical attenuation values for the continental fog case based on standard curve fitting technique. <em></em></span></span></p>

A compact planar ultra-wideband (UWB) multiple-input-multiple-output antenna array with two radiating elements is proposed in this work. Elements separation is kept at 5.5 mm and the isolation is achieved with a floating parasitic decoupling structure not known for UWB diversity antennas previously. The antenna system performs very well over the entire UWB frequency range of 3.1-10.6 GHz. The mutual coupling between the radiating elements is below -20 dB in most of the band. The decoupling structure is investigated in detail and the diversity analysis of the antenna in Rayleigh fading environment for indoor and outdoor propagations is also presented by computing envelope correlation coefficients. The proposed antenna array measures 33 x 45.5 mm(2) only and it is suitable for handheld devices, personal digital assistant (PDA)s, next generation home entertainment systems and robots

The major purpose of the study was to explore the impact of modular teaching on the achievements of students. The study was experimental type. Equivalent group study design was used. The collected data of both groups were analyzed and interpreted using mean, standard deviation and t-test, and conclusions were drawn. The results of the study were in the favor of modular teaching approach, therefore, it is suggested that this approach should be widely used in conventional classroom at various levels of education.

An eight element, compact Ultra Wideband− Multiple Input Multiple Output (UWB-MIMO) antenna capable of providing high data rates for future Fifth Generation (5G) terminal equipments along with the provision of necessary bandwidth for Third Generation (3G) and Fourth Generation (4G) communications that accomplishes band rejection from 4.85 to 6.35 GHz by deploying a Inductor Capacitor (LC) stub on the ground plane is presented. The incorporated stub also provides flexibility to reject any selected band as well as bandwidth control. The orthogonal placement of the printed monopoles permits polarization diversity and provides high isolation. In the proposed eight element UWB-MIMO/diversity antenna, monopole pair 3−4 are 180 • mirrored transform of monopole pair 1−2 which lie on the opposite corners of a planar 50 × 50 mm 2 substrate. Four additional monopoles are then placed perpendicularly to the same board leading to a total size of 50 × 50 × 25 mm 3 only. The simulated results are validated by comparing the measurements of a fabricated prototype. It was concluded that the design meets the target specifications over the entire bandwidth of 2 to 12 GHz with a reflection coefficient better than −10 dB (except the rejected band), isolation more than 17 dB, low envelope correlation, low gain variation, stable radiation pattern, and strong rejection of the signals in the Wireless Local Area Network (WLAN) band. Overall, compact and reduced complexity of the proposed eight element architecture, strengthens its practical viability for the diversity applications in future 5G terminal equipments amongst other MIMO antennas designs present in the literature. INDEX TERMS Band rejected, compact, diversity, envelope correlation coefficient , multiple input multiple output, ultrawide band, 5G communication, 5G terminal devices. I. INTRODUCTION W IRELESS broadband communication system such as Worldwide Interoperability for Microwave Access (WiMAX (3.4 to 3.6 GHz)), large capacity Microwave Relay Trunk Network (4.4 to 4.99 GHz), and Wireless Local Area Network (WLAN signals in 5.15 to 5.35 and 5.75 to 5.8225 GHz bands), impose a limited power spectral density of the low power and a high data rate

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