PCB based Modulated Scatter with Enhanced Modulation Depth

The Modulated Scatterer Technique (MST) Has Shown Promise for Applications in Microwave Imaging, Electric Field Mapping, and Materials Characterization. Traditionally, MST Scatterers Are Dipoles Centrally Loaded with an Element Capable of Modulation (E.g., a PIN Diode). by Modulating the Load Element State, the Scattered Fields Are Also Modulated. However, Due to the Small Size of Such Scatterers, It Can Be Difficult to Reliably Detect the Response. Increasing the Modulation Depth (MD) of the Scattered Signal May Improve Detectability. This Paper Presents Simulations and Measurements of PCB-Based MST Elements that, through Reactive Loading, Are Designed to Be Electrically Invisible during the Reverse Bias State of the Modulated Element (A PIN Diode in This Case) While Producing Detectable Scattering during the Forward Bias State. the Results Show a Significant (\u3e 90%) Improvement in the MD of the Scattered Signal When Compared to a Traditional MST Scatterer

Application of Electrically Invisible Antennas to the Modulated Scatterer Technique

The modulated scatterer technique (MST) has shown promise for applications in microwave imaging, electric field mapping, and materials characterization. Traditionally, MST scatterers are dipoles centrally loaded with an element capable of modulation (e.g., a p-i-n diode). By modulating the load element, signals scattered from the MST scatterer are also modulated. However, due to the small size of such scatterers, it can be difficult to reliably detect the modulated signal. Increasing the modulation depth (MD; a parameter related to how well the scatterer modulates the scattered signal) may improve the detectability of the scattered signal. In an effort to improve the MD, the concept of electrically invisible antennas is applied to the design of MST scatterers. This paper presents simulations and measurements of MST scatterers that have been designed to be electrically invisible during the reverse bias state of the modulated element (a p-i-n diode in this case), while producing detectable scattering during the forward bias state (i.e., operate in an electrically visible state). The results using the new design show significant improvement to the MD of the scattered signal as compared with a traditional MST scatterer (i.e., dipole centrally loaded with a p-i-n diode)

Application of Electrically Invisible Antennas to the Modulated Scatterer Technique

The Modulated Scatterer Technique (MST) has shown promise for application in microwave imaging, electric field mapping, and materials characterization. It is difficult to reliably detect the modulated scattered signal, due to the small size of the MST elements. Increasing the modulation depth (a parameter related to how well a scatterer modulates an incident signal) may improve the detection of the modulated scattered signal. In an effort to improve the modulation depth of MST scattering elements, the concept of electrically invisible antennas is applied to MST. This paper presents simulations and measurements of a traditional MST scatterer (a centrally-loaded resonant dipole) that has been designed to be electrically invisible. Building on this, an invisible dual-loaded scatterer is designed, with simulations showing significant improvement to the modulated depth as compared to a traditional modulated dipole

STICKY PIXELS-- - AN OFFICE SUPPLY SERENADE!

Our project objective was to create a multimedia art installation that is interactive and adapts/responds to users and/or to its environment. The final installation, Sticky Pixels: An Office Supply Serenade, allows multiple participants to create dynamic electronic music using colored sticky-notes and a specially designed robotic control system. This report comprehensively covers each step of the development and creation of our installation and details our time at the Boston Museum of Science displaying the final product to the general public

Non-Uniform Manual Scanning for Microwave Nondestructive Evaluation Imaging

Wide-band synthetic aperture radar (SAR) technique, capable of producing three-dimensional (3D) volumetric images, is a robust imaging tool for microwave and millimeter wave imaging involving nondestructive evaluation (NDE) applications. Conventionally, a relatively large number of measurement samples are required to image even a small area. Thus, it may take a relatively long time to perform the required scan and obtain an image. There is a significant push in the nondestructive testing community towards real-time imaging, particularly when dealing with large and critical structures (i.e., aircraft, bridges, space vehicles, etc.). Here, a method involving non-uniformly sampled wide-band reflection measurements data is described that enables the production of complete SAR images using only a fraction of the required measured data. The imaging method is based on a fast 3D wide-band SAR algorithm that produces 3D SAR images in real-time. Finally, a reconstruction algorithm is used to post-process the data resulting in high quality images with considerably lower background noise/clutter. This paper presents the measurement methodology along with a few experimentally obtained images

Coronal Heating as Determined by the Solar Flare Frequency Distribution Obtained by Aggregating Case Studies

Flare frequency distributions represent a key approach to addressing one of the largest problems in solar and stellar physics: determining the mechanism that counter-intuitively heats coronae to temperatures that are orders of magnitude hotter than the corresponding photospheres. It is widely accepted that the magnetic field is responsible for the heating, but there are two competing mechanisms that could explain it: nanoflares or Alfv\'en waves. To date, neither can be directly observed. Nanoflares are, by definition, extremely small, but their aggregate energy release could represent a substantial heating mechanism, presuming they are sufficiently abundant. One way to test this presumption is via the flare frequency distribution, which describes how often flares of various energies occur. If the slope of the power law fitting the flare frequency distribution is above a critical threshold, $\alpha=2$ as established in prior literature, then there should be a sufficient abundance of nanoflares to explain coronal heating. We performed $>$600 case studies of solar flares, made possible by an unprecedented number of data analysts via three semesters of an undergraduate physics laboratory course. This allowed us to include two crucial, but nontrivial, analysis methods: pre-flare baseline subtraction and computation of the flare energy, which requires determining flare start and stop times. We aggregated the results of these analyses into a statistical study to determine that $\alpha = 1.63 \pm 0.03$. This is below the critical threshold, suggesting that Alfv\'en waves are an important driver of coronal heating.Comment: 1,002 authors, 14 pages, 4 figures, 3 tables, published by The Astrophysical Journal on 2023-05-09, volume 948, page 7