A Novel Meander Bowtie-Shaped Antenna with Multi-Resonant and Rejection Bands for Modern 5G Communications

To support various fifth generation (5G) wireless applications, a small, printed bowtie-shaped microstrip antenna with meandered arms is reported in this article. Because it spans the broad legal range, the developed antenna can serve or reject a variety of applications such as wireless fidelity (Wi-Fi), sub-6 GHz, ultra-wideband (UWB) 5G communications due to its multiband characterization and optimized rejection bands. The antenna is built on an FR-4 substrate and powered via a 50-Ω microstrip feed line linked to the right bowtie’s side. The bowtie’s left side is coupled via a shorting pin to a partial ground at the antenna back side. A gradually increasing meandering microstrip line connected to both sides of the bowtie to enhance the rejection and operating bands. The designed antenna has seven operating frequency bands of (2.43 – 3.03) GHz, (3.71 – 4.23) GHz, (4.76 – 5.38) GHz, (5.83 – 6.54) GHz, (6.85 – 7.44) GHz, (7.56 – 8.01) GHz and (9.27 – 13.88) GHz. The simulated scattering parameter 11 reveals six rejection bands with percentage bandwidth of 33.87%, 15.73%, 11.71, 7.63%, 6.99%, 12.22% respectively. The maximum gain of the proposed antenna is 4.46 dB. The suggested antenna has been built, and the simulation and measurement results are very similar. The reported antenna is expanded to a four-element design to investigate their MIMO characteristics

Ultra-Low Phase Noise Microwaves from Optical Signals

Continuous-wave lasers locked to high-finesse optical reference cavities are oscillators that produce ~500 THz optical signals with unprecedented stability. Indeed, sub-femtosecond fractional frequency instability at one second averaging can now be achieved. A self-referenced femtosecond laser frequency comb (FLFC) is used as a frequency divider to provide a phase-coherent link between optical and microwave domains, dividing the frequency down to the gigahertz range while also transferring the stability of the original signal. Photodetectors then convert the optical pulses into electronic signals. The resultant 10 GHz microwave signals have ultra-low phase noise below -100 dBc/Hz at 1 Hz offset, surpassing that of traditional microwave oscillators. This new approach offers significant improvement for many applications that rely on stable microwave signals, and may even create new measurement technologies otherwise unachievable with current signal sources. In reality, fundamental and technical sources of noise in each stage of the optical-to-microwave generation process limit the ultimate achievable stability of the signal. Optical reference cavities are limited by environmental effects and thermal fluctuations, and FLFC dividers suffer from intrinsic timing jitter, amplitude noise, and limited stabilization servo bandwidth. However, it is the seemingly straightforward photodetection of optical pulses that proves to be the limiting factor in the ultimate noise floor of these signals. In this thesis, I describe the noise limitations of each part of the optical-to-microwave scheme, particularly focusing on the noise limitations of photodetection. I will give a basic representation of these photodetection noise phenomena in terms of the physical behavior of optically-generated electrons in semiconductor photodiodes. The two main photodetection noise phenomena--shot noise and amplitude-to-phase conversion--will be thoroughly characterized in the context of generation of 10 GHz low phase noise signals. Finally, I will use this characterization of photodetector noise to choose optimal photodetectors and operating conditions to realize unprecedentedly low phase noise signals with a variety of optical-to-microwave generation schemes

Solid State Technology Branch of NASA Lewis Research Center

A collection of papers written by the members of the Solid State Technology Branch of NASA LeRC from Jun. 1991 - Jun. 1992 is presented. A range of topics relating to superconductivity, Monolithic Microwave Circuits (MMIC's), coplanar waveguides, and material characterization is covered

Analysis and design of enhanced planar devices using multiconductor transmission lines with interconnected alternate lines

Novel capabilities and applications of multiconductor transmission lines with interconnected alternate lines have been analyzed in this work. The interconnections among alternate strips broaden the operating frequency band by eliminating undesired resonances and allow the use of simplified analytical models. Phase shifters, baluns, reconfigurable systems for the characterization of balanced circuits, ultra-wideband differential bandpass filters and quasi-elliptic bandpass filters have been proposed and demonstrated. For all these circuits a systematic design procedure have been derived and validated by means of experimental work. The excellent agreement between the measurements and the predicted results validates the proposed procedures as reliable and quick design techniques

Antenna Designs for 5G/IoT and Space Applications

This book is intended to shed some light on recent advances in antenna design for these new emerging applications and identify further research areas in this exciting field of communications technologies. Considering the specificity of the operational environment, e.g., huge distance, moving support (satellite), huge temperature drift, small dimension with respect to the distance, etc, antennas, are the fundamental device allowing to maintain a constant interoperability between ground station and satellite, or different satellites. High gain, stable (in temperature, and time) performances, long lifecycle are some of the requirements that necessitates special attention with respect to standard designs. The chapters of this book discuss various aspects of the above-mentioned list presenting the view of the authors. Some of the contributors are working strictly in the field (space), so they have a very targeted view on the subjects, while others with a more academic background, proposes futuristic solutions. We hope that interested reader, will find a fertile source of information, that combined with their interest/background will allow efficiently exploiting the combination of these two perspectives

Linear Operation of Switch-Mode Outphasing Power Amplifiers

Radio transceivers are playing an increasingly important role in modern society. The ”connected” lifestyle has been enabled by modern wireless communications. The demand that has been placed on current wireless and cellular infrastructure requires increased spectral efficiency however this has come at the cost of power efficiency. This work investigates methods of improving wireless transceiver efficiency by enabling more efficient power amplifier architectures, specifically examining the role of switch-mode power amplifiers in macro cell scenarios. Our research focuses on the mechanisms within outphasing power amplifiers which prevent linear amplification. From the analysis it was clear that high power non-linear effects are correctable with currently available techniques however non-linear effects around the zero crossing point are not. As a result signal processing techniques for suppressing and avoiding non-linear operation in low power regions are explored. A novel method of digital pre-distortion is presented, and conventional techniques for linearisation are adapted for the particular needs of the outphasing power amplifier. More unconventional signal processing techniques are presented to aid linearisation of the outphasing power amplifier, both zero crossing and bandwidth expansion reduction methods are designed to avoid operation in nonlinear regions of the amplifiers. In combination with digital pre-distortion the techniques will improve linearisation efforts on outphasing systems with dynamic range and bandwidth constraints respectively. Our collaboration with NXP provided access to a digital outphasing power amplifier, enabling empirical analysis of non-linear behaviour and comparative analysis of behavioural modelling and linearisation efforts. The collaboration resulted in a bench mark for linear wideband operation of a digital outphasing power amplifier. The complimentary linearisation techniques, bandwidth expansion reduction and zero crossing reduction have been evaluated in both simulated and practical outphasing test benches. Initial results are promising and indicate that the benefits they provide are not limited to the outphasing amplifier architecture alone. Overall this thesis presents innovative analysis of the distortion mechanisms of the outphasing power amplifier, highlighting the sensitivity of the system to environmental effects. Practical and novel linearisation techniques are presented, with a focus on enabling wide band operation for modern communications standards

Engineering Education and Research Using MATLAB

MATLAB is a software package used primarily in the field of engineering for signal processing, numerical data analysis, modeling, programming, simulation, and computer graphic visualization. In the last few years, it has become widely accepted as an efficient tool, and, therefore, its use has significantly increased in scientific communities and academic institutions. This book consists of 20 chapters presenting research works using MATLAB tools. Chapters include techniques for programming and developing Graphical User Interfaces (GUIs), dynamic systems, electric machines, signal and image processing, power electronics, mixed signal circuits, genetic programming, digital watermarking, control systems, time-series regression modeling, and artificial neural networks

Methodology for predicting and/or compensating the behavior of optical frequency comb

RESUMEN: Optical frequency comb spectrum can change its behavior due to temperature fluctuations, normal dispersion, and mechanical vibrations. Such limitations can affect the peak power and wavelength separation of comb lines. In the propagation through single−mode fiber, the linear and non−linear phenomena can modify spectral shape, phase shifts and flatness of spectrum. To find a strategy of compensation, the PhD thesis is focused on a prediction methodology based on fuzzy cellular automata, intuitionistic fuzzy sets and fuzzy entropy measures. The research work proposes a predictor called intuitionistic fuzzy cellular automata based on mean vector and a validation measure called general intuitionistic fuzzy entropy based on adequacy and non−adequacy. In the accomplished experiments, the method was used in three experiments: mode−locked lasers, cascaded intensity modulators−Mach Zehnder modulators, and microresonator ring. The obtained results showed that the power and phase distortions were reduced by using a pulse shaper, where the method was programmed. In addition, the stability and/or instability of spectrum were found for the microresonator ring

CAS - CERN Accelerator School: RF for Accelerators

These proceedings present the lectures given at the twenty-fourth specialized course organized by the CERN Accelerator School (CAS). The course was held in Ebeltoft, Denmark, from 8-17 June, 2010 in collaboration with Aarhus University, with the topic 'RF for Accelerators' While this topic has been covered by CAS previously, early in the 1990s and again in 2000, it was recognized that recent advances in the field warranted an updated course. Following introductory courses covering the background physics, the course attempted to cover all aspects of RF for accelerators; from RF power generation and transport, through cavity and coupler design, electronics and low level control, to beam diagnostics and RF gymnastics. The lectures were supplemented with several sessions of exercises, which were completed by discussion sessions on the solutions.These proceedings present the lectures given at the twenty-fourth specialized course organized by the CERN Accelerator School (CAS). The course was held in Ebeltoft, Denmark, from 8-17 June, 2010 in collaboration with Aarhus University, with the topic 'RF for Accelerators'. While this topic has been covered by CAS previously, early in the 1990s and again in 2000, it was recognized that recent advances in the field warranted an updated course. Following introductory courses covering the background physics, the course attempted to cover all aspects of RF for accelerators/ from RF power generation and transport, through cavity and coupler design, electronics and low level control, to beam diagnostics and RF gymnastics. The lectures were supplemented with several sessions of exercises, which were completed by discussion sessions on the solutions

Design and Control of Power Converters 2019

In this book, 20 papers focused on different fields of power electronics are gathered. Approximately half of the papers are focused on different control issues and techniques, ranging from the computer-aided design of digital compensators to more specific approaches such as fuzzy or sliding control techniques. The rest of the papers are focused on the design of novel topologies. The fields in which these controls and topologies are applied are varied: MMCs, photovoltaic systems, supercapacitors and traction systems, LEDs, wireless power transfer, etc