Abstract
The performance of Resonant Tunnelling Diode (RTD) oscillators with an optical window is evaluated experimentally, in the transmission of advanced modulation formats using electrical and optical modulation, for the first time. Additionally, the impact of phase noise in the transmission performance is also assessed.

Abstract
The high permittivity of InP substrates has been a limiting factor for the bandwidth and efficiency of antennas fabricated in this material. In this manuscript we propose an elliptical monopole, monolithically fabricated in InP, fed by a CPW line. The suggested topology was simulated using HFSS finite element method. Input reflection coefficient measurements were performed on the monopole to validate the proposed antenna. Simulated and measured -10 dB bandwidths of 27 and 24 GHz were obtained, respectively. The peak simulated efficiency and realized gain were 95.37% and 4.6 dBi.

Abstract
Optical modulation characteristics of resonant tunneling diode photodetectors (RTD-PD) are investigated. Intensity modulated light excites the RTD-PDs to conduct data experiments. Simple and complex data patterns are used with results showing data rates up to 80 and 200 Mbit/s, respectively. This is the first demonstration of complex modulation using resonant tunneling diodes.

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.