A High Performance Micromachined Sub-Millimeter-Wave Radar Technology

Motivated by the recent interest in high millimeter-wave (MMW) and sub-MMW radar sensors for applications ranging from navigation and mapping in autonomous systems to public safety and standoff detection of concealed weapons, this work presents the technology in support of a novel sub-MMW radar with minimal Size, Weight, and Power consumption (SWaP). This includes development of novel design, microfabrication, and measurement methods and techniques to develop the passive RF front-end of the radar system operating at 240 GHz. The sub-MMW radar system is designed for navigation and mapping applications in autonomous systems. The salient features of the proposed radar are its ultra-lightweight (less than 5 grams), compact form factor (2 cm3), low power consumption (6.7 mW for 1 fps), and ease of scalability to higher frequencies (up to 1 THz). This work introduces novel components and sub-systems for the RF front-end of the radar system. This includes developing high performance radar antenna systems as well as the chip packaging and integration technology with the associated transitions for realization of the radar system. In order to satisfy the requirements for high resolution and wide field of view for this imaging and navigation radar sensor, frequency scanning beam-steering antennas are developed to achieve ±25˚ of beam steering with a very narrow beam of 2.5˚ in the direction of scan. The designed array antenna has over 600 radiating elements and exhibits a radiation efficiency of over 55% and a gain of over 30 dBi over the entire operation frequency range. Additionally, for polarimetry applications, two versions of the antenna with both co- and cross-polarizations are developed to allow full-polarimetry imaging at sub-MMW frequencies. Another contribution of this work is development of a novel chip packaging methodology with the associated biasing network for sub-MMW integration of active and passive MMICs in the RF front-end. The packaging method offers a compact, low-loss, and wideband integration solution in the sub-MMW to terahertz (THz) frequency band which can be standardized for reliable and repeatable integrations at such frequencies. Due to the small wavelength at MMW to THz frequency band, fabrication of sub-MMW components requires high fabrication tolerances and accuracies, which is costly and hard to achieve with the standard machining techniques. To overcome this problem, in this work novel silicon micromachining methods are developed to enable reliable fabrication of complex structures, such as the radar RF front end, with low mass and low cost. The fabrication method allows seamless realization of the entire radar RF front-end on a single silicon block with a compact form factor and high level of integration. Repeatable and reliable characterization of sub-MMW components and sub-systems is a very challenging task and one major contribution of this dissertation pertains to development of novel measurement techniques to enable reliable on-wafer characterization of such devices in the MMW to THz band. This includes development of a novel waveguide probe measurement technique along with specially designed probes and the associated transitions for on-wafer S-parameter measurements at sub-MMW frequencies. Additionally, a novel on-wafer near-field measurement method is developed to allow pattern and power characterization of the antennas at sub-MMW frequencies. These methods are employed to perform full on-wafer characterization of the micromachined RF front-end components, including the antennas as well as the chip packaging, where excellent agreement of designed and measured results are shown.PHDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/140879/1/arminjam_1.pd

Modeling-Backed Microwave Imaging in Closed Systems: Reconstruction of a Spherical Inhomogeneity

This project contributes to the field of computational techniques for processing data in microwave imaging inside closed cavities. A computational procedure for imaging of a spherical inhomogeneity in a dielectric sample is outlined. It uses an artificial neural network capable of reconstructing geometrical and material parameters. The network uses data from an FDTD model. Computational experiments are reported for the 4-port waveguide element containing a Teflon sample with a hidden inclusion. The error in reconstruction of four geometrical parameters of a dielectric sphere is 3.3%; the error in finding complex permittivity of the inclusion is 9.8%. The project makes a solid theoretical background for the experimental program dedicated to multiport systems for practical applications

0.42 THz Transmitter with Dielectric Resonator Array Antenna

Off chip antennas do not occupy the expensive die area, as there is no limitation on their building material, and can be built in any size and shape to match the system requirements, which are all in contrast to on-chip antenna solutions. However, integration of off-chip antennas with Monolithic-Microwave-Integrated Chips (MMIC) and designing a low loss signal transmission from the signal source inside the MMIC to the antenna module is a major challenge and trade off. High resistivity silicon (HRS), is a low cost and extremely low loss material at sub-THz. It has become a prevailing material in fabrication of passive components for THz applications. This work makes use of HRS to build an off-chip Dielectric Resonator Antenna Array Module (DRAAM) to realize a highly efficient transmitter at 420 GHz. This work proposes novel techniques and solutions for design and integration of DRRAM with MMIC as the signal source. A proposed scalable 4×4 antenna structure aligns DRRAM on top of MMIC within 2 μm accuracy through an effortless assembly procedure. DRAAM shows 15.8 dB broadside gain and 0.85 efficiency. DRAs in the DRAAM are differentially excited through aperture coupling. Differential excitation not only inherently provides a mechanism to deliver more power to the antenna, it also removes the additional loss of extra balluns when outputs are differential inside MMIC. In addition, this work proposes a technique to double the radiation power from each DRA. Same radiating mode at 0.42 THz inside every DRA is excited through two separate differential sources. This approach provides an almost loss-less power combining mechanism inside DRA. Two 140_GHz oscillators followed by triplers drive each DRA in the demonstrated 4×4 antenna array. Each oscillator generates 7.2 dBm output power at 140 GHz with -83 dBc/Hz phase noise at 100 KHz and consumes 25 mW of power. An oscillator is followed by a tripler that generates -8 dBm output power at 420 GHz. Oscillator and tripler circuits use a smart layer stack up arrangement for their passive elements where the top metal layer of the die is grounded to comply with the planned integration arrangement. This work shows a novel circuit topology for exciting the antenna element which creates the feed element part of the tuned load for the tripler circuit, therefore eliminates the loss of the transition component, and maximizes the output power delivered to the antenna. The final structure is composed of 32 injection locked oscillators and drives a 4×4 DRAAM achieves 22.8 dBm EIRP

ANALYSIS AND DESIGN OF ANTENNA PROBES FOR DETECTION / IMAGING APPLICATIONS

Analysis and Design of Antenna Probes for Detection / Imaging Applications Ayman Elboushi, Ph.D. Concordia University. As a result of increasing international terrorist threats, the need for an efficient inspecting tool has become urgent. Not only for seeing through wall applications, but also to be employed as a safe human body scanner at public places such as airports and borders. The usage of microwave and millimeter wave antennas and systems for detection / imaging applications is currently of increasing research interest targeting the enhancement of different security systems. There are many challenges facing researchers in order to develop such systems. One of the challenges is the proper design of a low cost, reduced size and efficient antenna probe to work as a scanning sensor. In this thesis, two different technology choices of antenna probes for the feasibility of constructing detection / imaging systems are investigated. The first one covers the Ultra Wide Band (UWB) range (3.1 GHz to 10.6 GHz), while the second operates over the Millimeter-Wave (MMW) range. In addition to the development of several antenna probes, two detection / imaging systems are demonstrated and showed reasonably accurate detection results. Three different UWB monopole antenna prototypes, with different radiator shapes (circular, crescent and elliptical) have been introduced. These antennas are designed using a standard printed circuit board (PCB) process to work as probing sensors in a proposed UWB detection / imaging system. In order to enhance the resolution and the detection accuracy of the probe, 4-element Balanced Antipodal Vivaldi Antenna (BAVA) array fed by 1-to-4 UWB modified Wilkinson power divider has been developed. Some successful experiments have been conducted using the proposed UWB detection / imaging system combined with the fabricated antenna probes to detect the presence of a gap between two walls made of different material types, to evaluate the gap width and to estimate the size and exact location of a hidden target between the walls. The second research theme of this thesis is to develop small-sized, light-weight and high gain MMW scanning antenna probes. For the realization of such probes, several gain enhancement techniques have been adopted, including hybridization and a multi-element array principle. Several high-gain hybrid antennas have been designed, fabricated and tested. For demonstration purposes, experiments have been carried out for detecting and imaging a small metallic coin under the jeans layer of a three-layer target emulating a human body’s covering layers. A performance comparison between a standard metallic MMW horn and hybrid microstrip patch/conical horn antenna has been made. The proposed reduced size antenna sensor shows increased efficiency compared with the bulky horn antenna. Resolution enhancement of the reconstructed image of the hidden target is implemented using a new triple-antenna MMW sensor. The triple-antenna sensor consists of three adjacent microstrip patch / conical horn antennas separated by 1.5 wavelengths at the center frequency for coupling reduction between these elements. The middle element of the sensor is used for monitoring the time domain back-reflected signal from the target under inspection, while the side elements are used for monitoring the scattered signals. By the aid of a special signal processing algorithm, an enhanced image of the concealed object can be obtained by combining the three readings of each point in the area under study. The proposed system shows a great ability for detecting a hidden target and enhances the reconstructed image resolution

Millimeter-wave substrate integrated waveguides and components in thick-film technology

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Annual Report 2013 / Institute for Pulsed Power and Microwave Technology = Jahresbericht 2013 / Institut für Hochleistungsimpuls- und Mikrowellentechnik. (KIT Scientific Reports ; 7666)

The Institute for Pulsed Power and Microwave Technology (Institut für Hochleistungsimpuls- und Mikrowellentechnik - IHM) is doing research in the areas of pulsed power and high power microwave technologies. Both, research and development of high power sources as well as related applications are in the focus. Applications for pulsed power technologies are ranging from material processing to bioelectrics. Microwave technologies are focusing on RF sources for electron cyclotron resonance heating and on applications for material processing at microwave frequencies

NASA Tech Briefs, February 1993

Topics include: Communication Technology; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences; Life Sciences

Electromagnetic Waves

This book is dedicated to various aspects of electromagnetic wave theory and its applications in science and technology. The covered topics include the fundamental physics of electromagnetic waves, theory of electromagnetic wave propagation and scattering, methods of computational analysis, material characterization, electromagnetic properties of plasma, analysis and applications of periodic structures and waveguide components, and finally, the biological effects and medical applications of electromagnetic fields

NASA Tech Briefs, July 1992

Topics include: New Product Ideas; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences; Life Sciences