Antennas and Propagation

This Special Issue gathers topics of utmost interest in the field of antennas and propagation, such as: new directions and challenges in antenna design and propagation; innovative antenna technologies for space applications; metamaterial, metasurface and other periodic structures; antennas for 5G; electromagnetic field measurements and remote sensing applications

Belle II Technical Design Report

The Belle detector at the KEKB electron-positron collider has collected almost 1 billion Y(4S) events in its decade of operation. Super-KEKB, an upgrade of KEKB is under construction, to increase the luminosity by two orders of magnitude during a three-year shutdown, with an ultimate goal of 8E35 /cm^2 /s luminosity. To exploit the increased luminosity, an upgrade of the Belle detector has been proposed. A new international collaboration Belle-II, is being formed. The Technical Design Report presents physics motivation, basic methods of the accelerator upgrade, as well as key improvements of the detector.Comment: Edited by: Z. Dole\v{z}al and S. Un

Research Proposal for an Experiment to Search for the Decay {\mu} -> eee

We propose an experiment (Mu3e) to search for the lepton flavour violating decay mu+ -> e+e-e+. We aim for an ultimate sensitivity of one in 10^16 mu-decays, four orders of magnitude better than previous searches. This sensitivity is made possible by exploiting modern silicon pixel detectors providing high spatial resolution and hodoscopes using scintillating fibres and tiles providing precise timing information at high particle rates.Comment: Research proposal submitted to the Paul Scherrer Institute Research Committee for Particle Physics at the Ring Cyclotron, 104 page

1-D broadside-radiating leaky-wave antenna based on a numerically synthesized impedance surface

A newly-developed deterministic numerical technique for the automated design of metasurface antennas is applied here for the first time to the design of a 1-D printed Leaky-Wave Antenna (LWA) for broadside radiation. The surface impedance synthesis process does not require any a priori knowledge on the impedance pattern, and starts from a mask constraint on the desired far-field and practical bounds on the unit cell impedance values. The designed reactance surface for broadside radiation exhibits a non conventional patterning; this highlights the merit of using an automated design process for a design well known to be challenging for analytical methods. The antenna is physically implemented with an array of metal strips with varying gap widths and simulation results show very good agreement with the predicted performance

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

Radar Technology

In this book “Radar Technology”, the chapters are divided into four main topic areas: Topic area 1: “Radar Systems” consists of chapters which treat whole radar systems, environment and target functional chain. Topic area 2: “Radar Applications” shows various applications of radar systems, including meteorological radars, ground penetrating radars and glaciology. Topic area 3: “Radar Functional Chain and Signal Processing” describes several aspects of the radar signal processing. From parameter extraction, target detection over tracking and classification technologies. Topic area 4: “Radar Subsystems and Components” consists of design technology of radar subsystem components like antenna design or waveform design

Limited Angle Ultrasound Tomography of the Compressed Breast

X-ray mammography is widely accepted as the clinical standard for breast cancer screening and diagnosis. However, reflection mode ultrasound has been known to outperform x-ray in screening performance in dense breasts. With newer modes of ultrasound, acoustic properties of breast tissue, such as the speed of sound and attenuation coefficient distributions, can be extracted from captured ultrasound signals and used to characterize breast tissue types and contribute to detection and diagnosis of malignancy. The same is possibly true for optical absorption via photoacoustic imaging. Recently, we have developed a dual-sided ultrasound scanner that can be integrated with existing x-ray mammographic systems and acquire images in the mammographic view and compression. Transmission imaging for speed of sound and attenuation coefficient in this geometry is termed limited angle tomography, as the beams at frequencies yielding high resolution cannot transit the long axis of the compressed breast. This approach, ideally, should facilitate the co-registration and comparisons between images from three modalities discussed here (x-ray, ultrasound and photoacoustic) and increase diagnostic detection confidence. However, potential limitations inherent in limited angle tomography have received minimal exploration up to this study, and existing imaging techniques developed for this approach are based on overly optimistic assumptions that hinder achievement of the desired image quality. This investigation of these problems should contribute valuable information to the validation and translation of the mammographically-configured, dual-sided ultrasound, or ultrasound and photoacoustic, scanner to the clinic. This dissertation first aims to extensively identify possible sources of error resulting from imaging in the limited angle tomography approach. Simulation findings mapping parametric conditions reveal that image artifacts arising in reflection mode (B-mode) can be modulated or mitigated by ultrasound gels with adequate acoustic properties. In addition, sound speed imaging was performed determining the level of significance for several key sources of error. Results suggest that imaging in transmission mode is the most sensitive to transducer misplacement in the signal propagation direction. This misplacement, however, could be minimized easily by routinely calibrating transducer positions. Next, this dissertation aims to advance speed of sound, attenuation, and photoacoustic image reconstruction algorithms for the limited angle tomography approach. This was done by utilizing both structural information of the imaged objects/tissues by means of the corresponding reflection mode images taken from the same imaging location, and a full acoustic modeling framework to account for complex acoustic interactions within the field of view. We have shown through simulations that both a priori information from reflection mode images and full acoustic modeling contribute to a noticeable improvement in the reconstructed images. Work done throughout the course of this dissertation should provide a foundation and insight necessary for improvements upon the existing dual-sided ultrasound scanner towards breast imaging in the clinic.PHDBiomedical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/143944/1/rungroj_1.pd