OAM multiple transmission using uniform circular arrays: numerical modeling and experimental verification with two digital television signals

In this work we present the outcomes of a radio-frequency OAM transmission between two antenna arrays performed in a real-world context. The analysis is supplemented by deep simulative investigations able to provide both a preliminary overview of the experimental scenario and a posteriori validation of the achieved results. As a first step, the far-field OAM communication link is tested at various frequencies and the corresponding link budget is studied by means of an angular scan generated by the rotation of the receiving system. Then, on the same site, two digital television signals encoded as OAM modes ($\ell$=1 and $\ell$=-1) are simultaneously transmitted at a common frequency of 198.5 MHz with good mode insulation.Comment: 16 pages, 14 figure

Review of applications of the Laboratory for Electromagnetic Compatibility infrastructure

This article provides a thorough description of a range of non-standard application cases in which EMC laboratories can be used other than those traditionally associated with this kind of facilities. The areas covered here include investigations of: wireless and radio systems (such as IoT and broadband radio systems) also that require ultra-high operational dynamic range, emulation of interference-free and/or heavily-multipath propagation environment, shielding effectiveness of cabinets and materials (i.e. thin, light and flexible as textiles as well as heavy and thick such as building construction elements)

IMPACT OF SIGNAL RADIATION LEAKAGE ON POWER LINE COMMUNICATION SYSTEMS

Power Line Communication (PLC) is the usage of electrical power supply networks as a transmission medium for the transfer of various telecommunication services. However, PLC associated with the major cause of harmful interference (radiation leakage) to other users in transmission of information affects the full development and success of PLC. There is the need to develop a proper standard and regulations that will eliminate this problem globally. This study therefore, studies the impact of signal radiation leakage on Power Line Communication systems using Numerical Electromagnetic Code (NEC) method and field measurement to measure spacing along the power line and for measuring distance between the system frequencies in the power line. The result shows that the spacing between the wires on the power lines has effect on the radiation leakage. As wire spacing increases and external cancellation degrades, radiation escapes similar to those of long wire antennas. The result also shows that the frequencies of  power line operation lies between 444 kHz and 482 kHz. In general the PLC electric field along and near the power line decay with distance from the device but in at least one case, the electric field actually increased with increasing distance from the PLC device. Therefore, high levels of radiation suppression can be achieved only if the wires are very close together in terms of wavelength and balanced signals. Keywords: Power Line Communication(PLC) , Numerical Electromagnetic Code (NEC), Field Measurement, Electrical Power Network, Radiation Leakage, Frequency. DOI: 10.7176/MTM/9-8-02 Publication date: August 31st 201

The Quantum Socket: Three-Dimensional Wiring for Extensible Quantum Computing

Quantum computing architectures are on the verge of scalability, a key requirement for the implementation of a universal quantum computer. The next stage in this quest is the realization of quantum error correction codes, which will mitigate the impact of faulty quantum information on a quantum computer. Architectures with ten or more quantum bits (qubits) have been realized using trapped ions and superconducting circuits. While these implementations are potentially scalable, true scalability will require systems engineering to combine quantum and classical hardware. One technology demanding imminent efforts is the realization of a suitable wiring method for the control and measurement of a large number of qubits. In this work, we introduce an interconnect solution for solid-state qubits: The quantum socket. The quantum socket fully exploits the third dimension to connect classical electronics to qubits with higher density and better performance than two-dimensional methods based on wire bonding. The quantum socket is based on spring-mounted micro wires the three-dimensional wires that push directly on a micro-fabricated chip, making electrical contact. A small wire cross section (~1 mmm), nearly non-magnetic components, and functionality at low temperatures make the quantum socket ideal to operate solid-state qubits. The wires have a coaxial geometry and operate over a frequency range from DC to 8 GHz, with a contact resistance of ~150 mohm, an impedance mismatch of ~10 ohm, and minimal crosstalk. As a proof of principle, we fabricated and used a quantum socket to measure superconducting resonators at a temperature of ~10 mK.Comment: Main: 31 pages, 19 figs., 8 tables, 8 apps.; suppl.: 4 pages, 5 figs. (HiRes figs. and movies on request). Submitte

THz Ultra-wideband Passive Devices: Design, Simulation and Characterization

The last decades have seen an increasing interest in the THz research field, leading to a substantial improvement in technology and the emergence of new applications. In particular, the research on radio astronomy instrumentation has pushed millimeter and sub-millimeter technology boundaries and redefined state of the art.\ua0 Nonetheless, the requirements set for the next generation of radio astronomy receivers will demand remarkable technological development, especially in terms of RF and IF bandwidth. Addressing this need, the present licentiate thesis focuses on the design, simulation and characterization of ultra-wideband THz passive devices for the next generation of radio astronomy receivers. As THz receivers mixers are implemented with thin-film technology, waveguide to substrate transitions have a fundamental role in the performance and bandwidth of such systems. The critical requirements for these transitions are a proper impedance matching and the minimization of insertion loss. In this thesis, a waveguide to slotline superconducting transition based on substrateless finlines is proposed. The transition was designed for prospective broadband SIS mixer design in the frequency range 211-375 GHz. The experimental verification at cryogenic temperatures shows a remarkable fractional bandwidth of 55%. Although this transition represents a substantial improvement over existing designs, it is important to note that it transforms a waveguide propagation mode into slotline mode. For the majority of modern SIS mixers, microstrip line topology is the most suitable. Hence, the ongoing development is focused on broadband slotline to microstrip transitions. In this work, a slotline to microstrip transition based on Marchand Balun is designed, simulated and fabricated. The electromagnetic simulations showed promising results, and the cryogenic characterization at 4K is ongoing.For most modern polarization-sensitive THz receivers, 90\ub0 waveguide twists are essential interconnection parts. Since compactness and low insertion loss are critical requirements, single step-twists have emerged as an attractive solution. In this work, a novel compact wideband 90-degree twist for the 140-220 GHz band is presented. Furthermore, the proposed twist has a performance tolerant to small geometry variation, and hence it is especially suited for fabrication by direct milling. The experimental verification shows 44% fractional bandwidth with return loss better than 20 dB over most of the band

A Compact 3H(p,gamma)4He 19.8-MeV Gamma-Ray Source for Energy Calibration at the Sudbury Neutrino Observatory

The Sudbury Neutrino Observatory (SNO) is a new 1000-tonne D2O Cerenkov solar neutrino detector. A high energy gamma-ray source is needed to calibrate SNO beyond the 8B solar neutrino endpoint of 15 MeV. This paper describes the design and construction of a source that generates 19.8-MeV gamma rays using the 3H(p,gamma)4He reaction (``pt''), and demonstrates that the source meets all the physical, operational and lifetime requirements for calibrating SNO. An ion source was built into this unit to generate and to accelerate protons up to 30 keV, and a high purity scandium tritide target with a scandium-tritium atomic ratio of 1:2.0+/-0.2 was included. This pt source is the first self-contained, compact, and portable high energy gamma-ray source (E>10 MeV).Comment: 33 pages (including 2 table, 12 figures) This is the revised manuscript, accepted for publication in NIM A. This revision relfects minor editorial changes from the previous versio

Novel High Isolation Antennas for Simultaneous Transmit and Receive (STAR) Applications

Radio frequency (RF) spectrum congestion is a major challenge for the growing need of wireless bandwidth. Notably, in 2015, the Federal Communications Commission (FCC) auctioned just 65 MHz (a bandwidth smaller than that used for WiFi) for more than $40 billion, indicating the high value of the microwave spectrum. Current radios use one-half of their bandwidth resource for transmission, and the other half for reception. Therefore, by enabling radios to transmit and receive across their entire bandwidth allocation, spectral efficiency is doubled. Concurrently, data rates for wireless links also double. This technology leads to a new class of radios and RF frontends. Current full-duplex techniques resort to either time- or frequency-division duplexing (TDD and FDD respectively) to partition the transmit and receive functions across time and frequency, respectively, to avoid self-interference. But these approaches do not translate to spectral efficiency. Simultaneous transmit and receive (STAR) radios must isolate the transmitter from the receiver to avoid self-interference (SI). This SI prevents reception and must therefore be cancelled. Self-interference may be cancelled with one or more stages involving the antenna, RF or analog circuits, or digital filters. With this in mind, the antenna stage is the most critical to reduce the SI level and avoid circuit saturation and total system failure. This dissertation presents techniques for achieving STAR radios. The initial sections of the dissertation provide the general approach of stage to stage cancellation to achieve as much as 100 dB isolation between the receiver and transmitter. The subsequent chapters focus on different antennas to achieve strong transmit/receive isolation. As much as 35 dB isolation is shown using a new spiral antenna array with operation across a 2:1 bandwidth. Also, a new antenna feed is presented showing 42 dB isolation across a 250 MHz bandwidth. Reflections in the presence of a dynamic environment are also considered

Low Frequency Electric Field Imaging

abstract: Electric field imaging allows for a low cost, compact, non-invasive, non-ionizing alternative to other methods of imaging. It has many promising industrial applications including security, safely imaging power lines at construction sites, finding sources of electromagnetic interference, geo-prospecting, and medical imaging. The work presented in this dissertation concerns low frequency electric field imaging: the physics, hardware, and various methods of achieving it. Electric fields have historically been notoriously difficult to work with due to how intrinsically noisy the data is in electric field sensors. As a first contribution, an in-depth study demonstrates just how prevalent electric field noise is. In field tests, various cables were placed underneath power lines. Despite being shielded, the 60 Hz power line signal readily penetrated several types of cables. The challenges of high noise levels were largely addressed by connecting the output of an electric field sensor to a lock-in amplifier. Using the more accurate means of collecting electric field data, D-dot sensors were arrayed in a compact grid to resolve electric field images as a second contribution. This imager has successfully captured electric field images of live concealed wires and electromagnetic interference. An active method was developed as a third contribution. In this method, distortions created by objects when placed in a known electric field are read. This expands the domain of what can be imaged because the object does not need to be a time-varying electric field source. Images of dielectrics (e.g. bodies of water) and DC wires were captured using this new method. The final contribution uses a collection of one-dimensional electric field images, i.e. projections, to reconstruct a two-dimensional image. This was achieved using algorithms based in computed tomography such as filtered backprojection. An algebraic approach was also used to enforce sparsity regularization with the L1 norm, further improving the quality of some images.Dissertation/ThesisDoctoral Dissertation Electrical Engineering 201

RF and Microwave Measurements

open1noBasic theory and techniques are concentrated mostly in the first four chapters, where definitions, formulas and references are collected aiming at giving a thorough overview of the most relevant topics: circuit theory, material properties, transmission lines, signal analysis and spectral analysis, including random processes, probability and statistics. The central chapters 5, 6 and 7 deals with three important elements of setups and experiments: cables, printed circuit boards and connectors. The influence on the overall measurement, their modeling and characterization are discussed, keeping an eye on applicable standards. The last four chapters cover advanced aspects of scattering parameters, differential lines and mixed modes, and the use and performance of spectrum analyzer and vector network analyzer.openA. MariscottiMariscotti, A