Abstract
In this work we focus on the influence of salt water as the medium between two coupling coils to design a wireless power transfer system. An electrical circuit model and an adequate characterization approach is presented to account for the power losses in the conductive medium. Optimum values for the load and efficiency of the power link are determined. Experimental results are provided to compare the performance of the coupling coils between different coupling mediums (air, fresh and salt water).

Abstract
Triboelectric nanogenerators (TENGs) have been recognized as a promising harvesting technology to satisfy the power requirements of some marine activities. Our current work addresses the TENG design for the purpose of energy harvesting in the sea. In this paper we present a prototype currently under development, in which spheres made of a triboelectric material move within a limited volume due to external mechanical excitation. The spheres move along a printed circuit board having several electrodes and a PDMS film deposited on top, producing numerous voltage spikes. Experimental results are provided with time-domain wave forms and power characterization of the TENG.

Abstract

Abstract
In this paper we propose a high-gaussicity spline-profiled horn antenna, which is scalable in length and aperture to achieve higher gains whilst retaining a high Gaussian efficiency. A novel approach is used where a PSO is used for optimizing the spline, using the gaussicities at the operating frequencies as the objective function, which further improves side-lobe level and cross-polarization when compared to the state-of-the-art. With the proposed method, which was validated through FEM simulations in HFSS, reflection coefficients below -15 dB, gains greater than 25 dBi and gaussicities above 91% were obtained in the entire WR-3 band.

Abstract
In this paper, we present the design of an analog transmitter based on a blue LD targeting optical wireless communications, suitable for OFDM signals. The approach relies on a thorough characterization of the individual components of the module, whence a detailed circuit model is obtained to design an impedance matching circuit for improved performance, prior to fabrication. The impedance matching is based on non-uniform transmission lines and works well over a wide frequency range (100 MHz to 2 GHz). The results are experimentally validated by the transmitter response exhibiting an increased 6 dB bandwidth limit and 1 GHz bandwidth improvement. © 2020 IEEE.

Abstract
An OFDM transmission system is reported based on a directly modulated blue LASER diode, for high bit rate under-water optical communication applications. The 256 subcarriers 16-QAM signal is transmitted over a total distance of 2.4 m underwater with an EVM lower than -28.5 dB for a 250 MHz bandwidth and -16.5 dB for a 2 GHz bandwidth, the BER being lower than the forward error corrector limit. At the maximum bandwidth of 2 GHz a transmission rate of 5.36 Gbit/s is achieved. © 2020 IEEE.