A. Courtay

Bio: A. Courtay is an academic researcher from University of Michigan. The author has contributed to research in topics: Computer science & Antenna efficiency. The author has an hindex of 2, co-authored 2 publications receiving 227 citations.

Microstrip antennas on synthesized low dielectric-constant substrates

Abstract: Micromachining techniques using closely spaced holes have been used underneath a microstrip antenna on a high dielectric-constant substrate (/spl epsiv//sub r/=10.8) to synthesize a localized low dielectric-constant environment (/spl epsiv//sub r/=2.3). The measured radiation efficiency of a microstrip antenna on a micromachined 635-/spl mu/m thick /spl epsiv//sub r/=10.8 Duroid 6010 substrate increased from 48/spl plusmn/3% to 73/spl plusmn/3% at 12.8-13.0 GHz (including 3.3-cm feed line losses). We believe that this technique can be applied to millimeter-wave antennas (microstrip, dipoles, slots, etc.) on silicon and GaAs substrates to result in relatively wideband (3-6%) monolithic microwave integrated circuits (MMIC) active antenna modules for phased-arrays and collision-avoidance systems.

Microstrip antennas on localized micromachined dielectric substrates

Abstract: Micromachining techniques using closely spaced holes have been used underneath a microstrip antenna on a high dielectric constant substrate (/spl epsiv//sub /spl gamma//=10.8) to synthesize a localized low dielectric constant environment (/spl epsiv//sub /spl gamma//=2.3). The bandwidth of a 12.8 GHz microstrip antenna, was improved from 0.8% to 7.8%, and the measured radiation efficiency increased from 40% to 70%. We believe that this technique can be applied to millimeter-wave (30-100 GHz) microstrip antennas on GaAs substrates to result in relatively wideband (4-6%) MMIC active antenna modules for phased-arrays and collision avoidance systems.

LOLA SDR: Low Power Low Latency Software Defined Radio for Broadcast Audio Applications

Abstract: This brief proposes a new low power, low latency and low cost reconfigurable architecture for software defined radio. Due to their flexibility and reconfigurability, software defined radios are now massively used as wideband transceivers, channel sounders or network gateways. However, they often struggle to meet the desired requirements in terms of energy consumption and throughput. In this brief, we present a new architecture capable of tackling these challenges, by combining an off-the-shelf generic radio component with a low power microcontroller associated to a Fourier transform coprocessor. To prove the benefit of our approach, after describing the key assets of the architecture, we derive a complete physical layer dedicated to audio broadcast applications. This chain is capable of streaming High Definition audio stream in real time with low power (437mW) and very low latency (854 $\mu \text{s}$ ). We show that our processing chain can be flawlessly run on our architecture paving the way for larger adoption of a new generation of low power low latency software defined radio architectures.

Data Resolution Optimisation to Address Wireless Connectivity in Infrasound Measurement Systems

Abstract: Addressing wireless connectivity of infrasound sensor arrays in a continuous sensing operating scheme is a challenging task regarding channel capacity, legal limitations on ISM bands and required ranges. A decrease of the system throughput appears necessary. This paper discusses key trades on data radio transmission considering measurement constraints. We propose a self-noise analysis of a measurement system at the design stage. We demonstrate that an optimization of the samples resolution is possible, based on the effective number of bits of the system, achieving up to 20% reduction of the payload to transmit.

The revenge of asynchronous protocols: Wake-up Radio-based Multi-hop Multi-channel MAC protocol for WSN

Abstract: Synchronized MAC protocols are now considered as the ultimate solution to access the medium in wireless sensor networks. They guarantee both high throughout and constant latency and achieve reasonable energy consumption performance. However, synchronization is achieved at the cost of a complex framework with low flexibility on its parameters that is not suitable for some network topologies or application requirements. By contrast, asynchronous MAC protocols are versatile by nature but suffer from the tradeoff between energy consumption and latency. However, the addition of Wake-up Radio (WuR) can reduce the energy consumption of such protocols while maintaining very low latency thanks to its always-on feature and ultra-low power consumption. In this article, we present WuR-based Multi-hop Multi-channel (W2M), an asynchronous MAC protocol for wireless sensor networks. We also provide a fair comparison with Time Synchronized Channel Hopping (TSCH) through an extensive simulation campaign based on Contiki-NG and Cooja. Our results show that in low traffic scenarios, W2M outperforms TSCH in reducing both the energy consumption and the latency (at least 68% of energy is saved), but at the cost of slightly lower reliability.

Microstrip antennas integrated with electromagnetic band-gap (EBG) structures: a low mutual coupling design for array applications

Abstract: Utilization of electromagnetic band-gap (EBG) structures is becoming attractive in the electromagnetic and antenna community. In this paper, a mushroom-like EBG structure is analyzed using the finite-difference time-domain (FDTD) method. Its band-gap feature of surface-wave suppression is demonstrated by exhibiting the near field distributions of the electromagnetic waves. The mutual coupling of microstrip antennas is parametrically investigated, including both the E and H coupling directions, different substrate thickness, and various dielectric constants. It is observed that the E-plane coupled microstrip antenna array on a thick and high permittivity substrate has a strong mutual coupling due to the pronounced surface waves. Therefore, an EBG structure is inserted between array elements to reduce the mutual coupling. This idea has been verified by both the FDTD simulations and experimental results. As a result, a significant 8 dB mutual coupling reduction is noticed from the measurements.

Electromagnetic Band Gap Structures in Antenna Engineering

Abstract: Preface 1. Introduction 2. FDTD Method for periodic structure analysis 3. EBG Characterizations and classifications 4. Design and optimizations of EBG structures 5. Patch antennas with EBG structures 6. Low profile wire antennas on EBG surfaces 7. Surface wave antennas Appendix: EBG literature review.

Aperture-coupled patch antenna on UC-PBG substrate

Abstract: The recently developed uniplanar compact photonic bandgap (UC-PBG) substrate is successfully used to reduce surface-wave losses for an aperture-coupled fed patch antenna on a thick high dielectric-constant substrate. The surface-wave dispersion diagram of the UC-PBG substrate has been numerically computed for two different substrate thickness (25 and 50 mil) and found to have a complete stopband in the frequency range of 10.9-13.5 and 11.4-12.8 GHz, respectively. The thicker substrate is then used to enhance broadside gain of a patch antenna working in the stopband at 12 GHz. Computed results and measured data show that, due to effective surface-wave suppression, the antenna mounted on the UC-PBG substrate has over 3-dB higher gain in the broadside direction than the same antenna etched on a grounded dielectric slab with same thickness and dielectric constant. Cross-polarization level remains 13 dB down the co-polar component level for both E- and H-planes.

Micromachined devices for wireless communications

Abstract: An overview of recent progress in the research and development of micromachined devices for use in wireless communication subsystems is presented. Among the specific devices described are tunable micromachined capacitors, integrated high-Q inductors, micromachined low-loss microwave and millimeter-wave filters, low-loss micromechanical switches, microscale vibrating mechanical resonators with Q's in the tens of thousands, and miniature antennas for millimeter-wave applications. Specific applications are reviewed for each of these components with emphasis on methods for miniaturization and performance enhancement of existing and further wireless transceivers.

Directive photonic-bandgap antennas

Abstract: This paper introduces two new photonic bandgap (PBG) material applications for antennas, in which a photonic parabolic reflector is studied. It is composed of dielectric parabolic layers associated to obtain a PBG material. The frequency gap is used to reflect and focus the electromagnetic waves. This device has been designed using a finite-difference time-domain (FDTD) code. FDTD computations have provided the theoretical reflector's directivity. These results are in good agreement with measurements, and it appears that the PBG reflector presents the same directivity as a metallic parabola. A second application uses a defect PBG material mode associated with a metallic plate to increase the directivity of a patch antenna. We explain the design of such a device and propose experimental results to validate the theoretical analysis.