Abstract
We report on the direct intensity modulation characteristics of a high-speed resonant tunneling diode-photodetector (RTD-PD) with an oscillation frequency of 79 GHz. This work demonstrates both electrical and optical modulation and shows that RTD-PD oscillators can be utilized as versatile optoelectronic/radio interfaces. This is the first demonstration of optical modulation of an RF carrier using integrated RTD-PD oscillators at microwave frequencies. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement.

Abstract
In this letter, a packaged compact meander-line monopole antenna for Bluetooth communications, manufactured in low-density fan-out technology, is presented. A combined size for the antenna and ground plane of 0.1 lambda(0) x 0.06 lambda(0) x 0.008 lambda(0) is obtained. Such small antennas are usually designed considering their connection to an evaluation board with a large ground plane, which improves their gain and bandwidth, but in this letter, the antenna is designed so it can work standalone without any further connection to printed circuit boards. The challenge of designing such a compact antenna is surpassed by performing a detailed modeling of the radiating meander-line element altogether with its finite ground plane, a tuning inductor, and an inductive coupling feed. The antenna model is developed in Ansys HFSS using the finite element method, which is later validated experimentally. Measurements of the return loss radiation pattern are carried out, and final results show a -6 dB bandwidth of approximately 110 MHz and a gain of -8.7 dBi, at 2.42 GHz.

Abstract
In this paper we evaluate the long-term deployment feasibility of a large-scale network of abandoned underwater sensors, where power is provided by autonomous underwater vehicles (AUVs) in periodic visits.

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 describe the design of a dual polarized packaged patch antenna for 5G communications with improved isolation and bandwidth for Ka-band. The results were validated using FEM and Momentum co-simulations in ADS. The novelty of the approach is the use of parasitic elements in the same layer to circumvent bandwidth limitations, thereby reducing the layer count in contrast to previous designs, combined with a differential feeding technique for improved isolation and radiation pattern stability, albeit at the expense of an increased complexity in the matching process. A peak gain of 5 dBi, isolation above 40 dB and a radiation efficiency of 60% were obtained. © 2019 IEEE.