Concepts for Short Range Millimeter-wave Miniaturized Radar Systems with Built-in Self-Test

This work explores short-range millimeter wave radar systems, with emphasis on miniaturization and overall system cost reduction. The designing and implementation processes, starting from the system level design considerations and characterization of the individual components to final implementation of the proposed architecture are described briefly. Several D-band radar systems are developed and their functionality and performances are demonstrated

Low Temperature Co-fired Ceramics for System-in-Package Applications at 122 GHz

This work presents a low temperature co-fired ceramic (LTCC) technology based system-in-package (SiP) operating beyond 100 GHz. The SiP encloses a semiconductor transceiver chip in a pea-sized LTCC package. The SiP is efficient and robust in terms of its electrical, thermal and mechanical characteristics. Moreover, it is low-cost and requires only standard manufacturing and assembly techniques. Finally, two fully-integrated 122 GHz radar sensors are demonstrated in LTCC technology

Switched-beam antenna array design for millimeter-wave applications

The limited coverage of wireless communication at the millimeter-wave frequency band due to large free-space path loss, i.e. large signal attenuation, has been a major problem. Furthermore, shadowing and small-scale fading may reduce the received signal even more. An array of rod antennas is designed to tackle those problems by providing high gain, broad scan range, and a shaped beam. Each patch, which couples the electromagnetic wave to the rod, is fed by a coplanar waveguide (CPW) feedline. Each rod antenna demonstrates 18 dBi realized gain and 20° half power beamwidth (HPBW). Moreover, the 4 GHz bandwidth of the antenna provides high data rate for the gigabit wireless application. Furthermore, the Radio Frequency Microelectromechanical System (RF MEMS) switch is used to realize a switched antenna with a broad scan range. The design method and the characterization of the antenna are presented. The proposed antenna system is suitable for a wide range of applications, such as wireless high definition video/audio, USB and firewire replacement, Frequency Modulated Continuous Wave (FMCW) radar, and home/office backhaul application at millimeter-wave frequency

Time domain based image generation for synthetic aperture radar on field programmable gate arrays

Aerial images are important in different scenarios including surface cartography, surveillance, disaster control, height map generation, etc. Synthetic Aperture Radar (SAR) is one way to generate these images even through clouds and in the absence of daylight. For a wide and easy usage of this technology, SAR systems should be small, mounted to Unmanned Aerial Vehicles (UAVs) and process images in real-time. Since UAVs are small and lightweight, more robust (but also more complex) time-domain algorithms are required for good image quality in case of heavy turbulence. Typically the SAR data set size does not allow for ground transmission and processing, while the UAV size does not allow for huge systems and high power consumption to process the data. A small and energy-efficient signal processing system is therefore required. To fill the gap between existing systems that are capable of either high-speed processing or low power consumption, the focus of this thesis is the analysis, design, and implementation of such a system. A survey shows that most architectures either have to high power budgets or too few processing capabilities to match real-time requirements for time-domain-based processing. Therefore, a Field Programmable Gate Array (FPGA) based system is designed, as it allows for high performance and low-power consumption. The Global Backprojection (GBP) is implemented, as it is the standard time-domain-based algorithm which allows for highest image quality at arbitrary trajectories at the complexity of O(N3). To satisfy real-time requirements under all circumstances, the accelerated Fast Factorized Backprojection (FFBP) algorithm with a complexity of O(N2logN) is implemented as well, to allow for a trade-off between image quality and processing time. Additionally, algorithm and design are enhanced to correct the failing assumptions for Frequency Modulated Continuous Wave (FMCW) Radio Detection And Ranging (Radar) data at high velocities. Such sensors offer high-resolution data at considerably low transmit power which is especially interesting for UAVs. A full analysis of all algorithms is carried out, to design a highly utilized architecture for maximum throughput. The process covers the analysis of mathematical steps and approximations for hardware speedup, the analysis of code dependencies for instruction parallelism and the analysis of streaming capabilities, including memory access and caching strategies, as well as parallelization considerations and pipeline analysis. Each architecture is described in all details with its surrounding control structure. As proof of concepts, the architectures are mapped on a Virtex 6 FPGA and results on resource utilization, runtime and image quality are presented and discussed. A special framework allows to scale and port the design to other FPGAs easily and to enable for maximum resource utilization and speedup. The result is streaming architectures that are capable of massive parallelization with a minimum in system stalls. It is shown that real-time processing on FPGAs with strict power budgets in time-domain is possible with the GBP (mid-sized images) and the FFBP (any image size with a trade-off in quality), allowing for a UAV scenario

Investigative Development of an UWB Radar for UAS-borne Applications

The engineering ethos of the last decade has been miniaturization. Progress in various industries like material design, semiconductor technology, and digital signal processing has resulted in low-profile electrical systems. This has facilitated the means of integration onto platforms. Sensors such as radars are typically large, heavy, and consume a lot of power. Miniaturization of radars can enable important applications like remote sensing the various aspects of the Earth System from Unmanned Aerial Systems (UAS). Information about natural topography like ice sheets, vegetation cover, and ocean currents can improve our understanding of the natural processes and continued measurements offer insight into the changes over time. Soil plays a vital role in the Earth’s hydrological cycle. The moisture in soil influences the weather, vegetation, and human endeavors like construction. Models are built using an extensive set of temporal soil moisture data to predict natural disasters like droughts, floods, and landslides. It plays a central role in the areas of agriculture and water resource management and hence can influence policy making and economic decisions. In this work, an investigative approach to the design, build, and test of a 2 – 18 GHz Frequency Modulated Continuous Wave radar for snow and soil measurements is reported. The radar system is designed to be integrated to the Vapor 55 rotorcraft, which is a Group 1 UAS. The radar can operate as a scatterometer to measure backscatter signatures in all four combinations of vertical and horizontal polarizations; or as a nadir-looking sounder for fine-resolution snow thickness measurements. One of the primary contributions of this work is the exploration of a single-module that integrates the radar’s RF transmitter, RF receiver, receiver’s IF section, wideband sweep generator, and the DC bias circuitry for the active components. The sweep generator is based on a phase-locked loop and frequency multiplication/translation stage. The compact assembly is in the form of two multilayer Printed Circuit Boards (PCB) merged together and it occupies an area of nearly 170 cm2. This thesis describes the design, construction, and testing of the module, along with recommendations for future revisions. A commercially off-the-shelf module (Arena series by Tomorrow.io, formerly Remote Sensing Solutions) is the digital backend and it consists of an Arbitrary Waveform Generator (AWG) and a data acquisition system capable of sampling up to 250 MSPS. The module is low-profile with dimensions of 7.6 cm x 19.3 cm x 2.3 cm and weighs less than 400 g including the separate aluminum enclosure intended to be integrated with the radar’s RF and mixed-signal sections. A second contribution of this work is the design of a prototype antenna front-end, which consists of four four-element antenna arrays housed in a Delrin plastic fixture and are fed using custom-designed microstrip power dividers. The dimensions of the fixture are 13.7 cm x 5.9 cm x 5.5 cm and the uniform elemental distance is 2.5 cm. The arrays are fastened to a metal sheet and a custom-designed four-layer fiberglass composite fairing protects the arrays. The entire front-end is integrated on the rotorcraft and measured in an anechoic chamber. The measured, fully integrated return loss of each array covers 2 – 18 GHz and the highest value is -7.22 dB at 5.23 GHz. The radiation pattern shows a distinct nadir-pointing main lobe for nearly the entire bandwidth, however the effects of the platform increase the average side-lobe levels to less than 10 dB for 12 – 18 GHz. The measured maximum nadir gain is 15.88 dB at 10 GHz and there is a greater than 6 dB variation in magnitude within the bandwidth. This variation is compensated by processing the backscatter data over distinct sub-bands that have a maximum nadir gain variation of 6 dB. Lastly, the thesis describes two system tests conducted to evaluate the effectiveness of a prototype radar with soil as the target. These are proof-of-concept measurements to detect differences in backscatter signatures between dry and wet soil. Gravimetric measurements of collected soil samples indicate an average change of 9.5% between the two moisture states. The antenna front-end is exclusively characterized using a Vector Network Analyzer and measurements are recorded for both co- and cross-polarization at three look angles of nadir, 15°, and 30°. The relative measurements are repeated on the same patch of land with a 1U version of the miniaturized radar. There are distinct differences in relative received power and backscatter profile for all four polarizations and at each look angle. It is observed that vertical polarization indicates a change in moisture content by an increase in the relative received power over an extended range beyond the primary backscatter signal. The horizontal polarization results in a greater peak received power for the primary backscatter signal, relative to the vertical polarization. The degradation in backscatter profile for vertical polarization is higher than horizontal polarization as a function of angle and this is observed for both dry and wet soil.The ETD Release form has been added to this record as a License bitstrea

Development of a Multichannel Wideband Radar Demonstrator

With the rise of software defined radios (SDR) and the trend towards integrating more RF components into MMICs the cost and complexity of multichannel radar develop- ment has gone down. High-speed RF data converters have seen continuous increases in both sampling rate and resolution, further rendering a growing subset of components in an RF chain unnecessary. A recent development in this trend is the Xilinx RF- SoC, which integrates multiple high speed data converters into the same package as an FPGA. The Center for Remote Sensing of Ice Sheets (CReSIS) is regularly upgrading its suite of sensor platforms spanning from HF depth sounders to Ka band altimeters. A radar platform was developed around the RFSoC to demonstrate the capabilities of the chip when acting as a digital backend and evaluate its role in future radar designs at CReSIS. A new ultra-wideband (UWB) FMCW RF frontend was designed that con- sists of multiple transmit and receive modules with a 6 GHz bandwidth centered at 5 GHz. An antenna array was constructed out of Vivaldi elements to validate radar system performance. Firmware developed for the RFSoC enables radar features such as beam forming, frequency notching, dynamic stretch processing, and variable gain correction. The feature set presented here may prove useful in future sensor platforms used for the remote sensing of snow, soil moisture, or crop canopies

BiCMOS Millimetre-wave low-noise amplifier

Abstract: Please refer to full text to view abstract.D.Phil. (Electrical and Electronic Engineering

Antenna System Design for 5G and Beyond – A Modal Approach

Antennas are one of the key components that empower a new generation of wireless technologies, such as 5G and new radar systems. It has been shown that antenna design strategies based on modal theories represent a powerful systematic approach to design practical antenna systems with high performance. In this thesis, several innovative multi-antenna systems are proposed for wireless applications in different frequency bands: from sub-6 GHz to millimeter-wave (mm-wave) bands. The thesis consists of an overview (Part I) and six scientific papers published in peer-reviewed international journals (Part II). Part I provides the overall framework of the thesis work: It presents the background and motivation for the problems at hand, the fundamental modal theories utilized to address these problems, as well as subject-specific research challenges. Brief conclusions and future outlook are also provided. The included papers of Part II can be divided into two tracks with different 5G and beyond wireless applications, both aiming for higher data rates.In the first track, Papers [I] to [IV] investigate different aspects of antenna system design for smart-phone application. Since Long Term Evolution (LTE) (so-called 3.5G) was deployed in 2009, mobile communication systems have utilized multiple-input multiple-output antenna technology (MIMO) technology to increase the spectral efficiency of the transmission channel and provide higher data rates in existing and new sub-6 GHz bands. However, MIMO requires multi-antennas at both the base stations and the user equipment (mainly smartphones) and it is very challenging to implement sub-6 GHz multi-antennas within the limited space of smartphones. This points to the need for innovative design strategies. The theory of characteristic modes (TCM) is one type of modal theory in the antenna community, which has been shown to be a versatile tool to analyze the inherent resonance properties of an arbitrarily shaped radiating structure. Characteristic modes (CMs) have the useful property of their fields being orthogonal over both the source region and the sphere at infinity. This property makes TCM uniquely suited for electrically compact MIMO antenna design.In the second track, Papers [V]-[VI] investigate new integrated antenna arrays and subarrays for the two wireless applications, which are both implemented in a higher part of the mm-wave frequency range (i.e. E-band). Furthermore, a newly developed high resolution multi-layer “Any-Layer” PCB technology is investigated to realize antenna-in-package solutions for these mmwave antenna system designs. High gain and high efficiency antennas are essential for high-speed wireless point-to-point communication systems. To meet these requirements, Paper [V] proposes directive multilayer substrate integrated waveguide (SIW) cavity-backed slot antenna array and subarray. As a background, the microwave community has already shown the benefits of modal theory in the design and analysis of closed structures like waveguides and cavities. Higher-order cavity modes are used in the antenna array design process to facilitate lower loss, simpler feeding network, and lower sensitivity to fabrication errors, which are favorable for E-band communication systems. However, waveguide/cavity modes are confined to fields within the guided media and can only help to design special types of antennas that contain those structures. As an example of the versatility of TCM, Paper [VI] shows that apart from smartphone antenna designs proposed in Papers [I]-[IV], TCM can alsobe used to find the desirable modes of the linear antenna arrays. Furthermore, apart from E-band communications, the proposed series-fed patch array topology in Paper [VI] is a good candidate for application in 79 GHz MIMO automotive radar due to its low cost, compact size, ability to suppress surface waves, as well as relatively wide impedance and flat-gain bandwidths