Compact UWB MIMO Antenna for 5G Millimeter-Wave Applications.

This paper presents a printed multiple-input multiple-output (MIMO) antenna with the advantages of compact size, good MIMO diversity performance and simple geometry for fifth-generation (5G) millimeter-wave (mm-Wave) applications. The antenna offers a novel Ultra-Wide Band (UWB) operation from 25 to 50 GHz, using a Defective Ground Structure (DGS) technology. Firstly, its compact size makes it suitable for integrating different telecommunication devices for various applications, with a prototype fabricated having a total size of 33 mm × 33 mm × 0.233 mm. Second, the mutual coupling between the individual elements severely impacts the diversity properties of the MIMO antenna system. An effective technique of orthogonally positioning the antenna elements to each other increased their isolation; thus, the MIMO system provides the best diversity performance. The performance of the proposed MIMO antenna was investigated in terms of S-parameters and MIMO diversity parameters to ensure its suitability for future 5G mm-Wave applications. Finally, the proposed work was verified by measurements and exhibited a good match between simulated and measured results. It achieves UWB, high isolation, low mutual coupling, and good MIMO diversity performance, making it a good candidate and seamlessly housed in 5G mm-Wave applications.

Performance analysis of serial relay orbital satellite optical communication over turbulent channels.

Optical space communication has been proven to be a reliable relay satellite transmission system. The difficulty that occurs in RF satellite communication (SatCom) can be alleviated by using free-space optical (FSO) or laser SatCom. In this work, we analyze a proposed laser downlink relay SatCom model with existing channel turbulence employing intensity modulation and direct detection (IM/DD), and amplify-and-forward (AF) technology and compare it with the optical direct link SatCom. Accounting for atmospheric attenuation and turbulence, the effect of model parameters such as zenith angle, receiver aperture radius, best number of optical ground stations (OGSs), and end-to-end operating wavelength on system performance is investigated for different OGS height scenarios. We provide exact closed-form expressions for the proposed model and optimize system performance by selecting the best number of OGSs using a selective diversity technique that can boost the system signal-to-noise (SNR) by up to 37 dB (99.9%).