Optical phase synchronization in coherent optical beamformers for phased array receive antennas

Optical phase synchronization is an important issue in coherent optical beamforming systems. In this kind of architectures, the optical carrier produced by a common laser is split and then modulated by the RF signals coming from different antenna elements, delayed as desired, and combined in couplers. At the combining points it is fundamental that the optical carriers on the two branches are in phase, so that constructive interference can occur at the detector, resulting in maximized optical power and, as a consequence, maximized RF signal power. The issue of optical phase synchronization becomes particularly sensitive when dealing with hybrid setups, where the integrated optical chips are connected by means of optical fibers. In this case, a number of causes concur to de-synchronize the optical phases, originating destructive interference and dramatically reducing the output signal-to-noise ratio of the system. In this thesis, several solutions to this problem are proposed and analyzed. The total power feedback loop technique is then chosen as the most suitable approach, and shown to be a valid solution to synchronize the optical phases. Several feedback algorithms are analyzed and simulated in their pros and cons, and then an optimum hybrid algorithm is chosen to allow, at the same time, local maxima avoidance and fast tracking against phase drifts. The performance of this solution was first simulated, optimized in its parameters and nally implemented and tested in the real system. This work proved that, by means of the designed feedback loop, the optical output power is successfully stabilized at the maximum value despite the drifting in the hybrid setup parameters.Ingeniería de Telecomunicació

Analysis and design of smart antenna arrays (SAAs) for improved directivity at GHz range for wireless communication systems.

Doctor of Philosophy in Electronic Engineering. University of KwaZulu-Natal, Durban 2018.Abstract available in PDF file

Practical investigation of Butler matrix application for beamforming with circular antenna arrays

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Beam scanning by liquid-crystal biasing in a modified SIW structure

A fixed-frequency beam-scanning 1D antenna based on Liquid Crystals (LCs) is designed for application in 2D scanning with lateral alignment. The 2D array environment imposes full decoupling of adjacent 1D antennas, which often conflicts with the LC requirement of DC biasing: the proposed design accommodates both. The LC medium is placed inside a Substrate Integrated Waveguide (SIW) modified to work as a Groove Gap Waveguide, with radiating slots etched on the upper broad wall, that radiates as a Leaky-Wave Antenna (LWA). This allows effective application of the DC bias voltage needed for tuning the LCs. At the same time, the RF field remains laterally confined, enabling the possibility to lay several antennas in parallel and achieve 2D beam scanning. The design is validated by simulation employing the actual properties of a commercial LC medium

Advanced Radio Frequency Antennas for Modern Communication and Medical Systems

The main objective of this book is to present novel radio frequency (RF) antennas for 5G, IOT, and medical applications. The book is divided into four sections that present the main topics of radio frequency antennas. The rapid growth in development of cellular wireless communication systems over the last twenty years has resulted in most of world population owning smartphones, smart watches, I-pads, and other RF communication devices. Efficient compact wideband antennas are crucial in RF communication devices. This book presents information on planar antennas, cavity antennas, Vivaldi antennas, phased arrays, MIMO antennas, beamforming phased array reconfigurable Pabry-Perot cavity antennas, and time modulated linear array