EMAG Technologies (United States)

This study explored the chaotic properties of human emotions as expressed in social media and its implications for attainable forecasting horizons. Three human emotional states extracted from Twitter were analyzed using the nonlinear dynamics approach. The greatest positive Lyapunov exponent (LE) and 0-1 test methods were applied to a time series set consisting of over 25,000 data points reflecting the hourly recorded data of over 1.3 million tweets. The results suggest that the examined emotional time series data represent a nonlinear dynamical system with deterministic chaos properties. Therefore, by utilizing traditional linear methods of social media data analysis, one may not be able to fully understand and forecast critical transition trends over time or beyond a limited duration. It was concluded that the nonlinear dynamics approach is useful to determine a feasible forecasting horizon and to assess the prediction accuracy of social media data in general.

A microwave radiometer specifically designed to detect and mitigate many types of Radio Frequency Interference (RFI) is described. The L-band RFI Detection and Mitigation Testbed (DetMit Testbed) will not be optimized for radiometric observation as much as it is optimized for flexibility in the presence of RFI. While the DetMit Testbed will be a fully functional polarimetric L-band radiometer, the ultimate application of this instrument is not so much brightness measurements as it will be validation of RFI mitigation strategies for employment in future L-band (and other frequency) radiometers. The design approaches for the L-band RFI Detection and Mitigation Testbed are expected to apply to C- band and X-band, and presumably also to other frequencies of interest that experience RFI.

Five types of micromachined vertical transitions appropriate for high frequency packaging are presented. The transitions are designed, fabricated and tested for silicon wafers. A "top-via" transition for on-wafer packaging is introduced. This design combines the packaging cavity and the RF transition on a single wafer in order to simplify the integration. This approach offers increased flexibility in the fabrication and encapsulation of on-wafer packaged devices. The remaining transitions are: a microstrip-to-microstrip transition, based on the use of a short finite ground coplanar waveguide (FGC) section for improved impedance matching. In addition, a microstrip-to-FGC, a FGC-to-microstrip, and a FGC-to-FGC transitions are presented.

Evanescent-mode filters are realized by both silicon micromachining as well as layer-by-layer polymer stereolithography (SL) processing. Capacitive loading an enclosed resonator reduces the size of a distributed cavity to be much smaller than a wavelength but which has much higher unloaded Q than lumped elements. The loaded resonators are extended into reduced-size filters with a low insertion loss due to the relatively high quality factor. Size reduction of resonators and filters can be a full order of magnitude depending on the height of the capacitive post. A 14 GHz resonator micro-machined in silicon with 5 mm/spl times/5 mm/spl times/0.45 mm volume reduces the size by 76.8%. The polymer-based fabrication was used to create a resonator with a Q greater than 1,050. An insertion loss of 0.83 dB was measured in a 1.69% filter with a size reduction of 47%. Furthermore, the proposed filters are quasi-planar and capable of integration with other RF components.

This paper presents a novel design for compact multifunction antennas for wireless applications. To reduce the physical size of the antenna, a high permittivity substrate or superstrate is utilized. In order to suppress the surface waves in the dielectric slab, a grading of the index profile is proposed in both axial and radial directions. Furthermore, the index grading can be done in the antenna feed area to achieve impedance matching. A low-cost and easy-to-manufacture way of achieving the graded index profile is proposed, whereby a set of air voids are created inside the dielectric material to realize an effective dielectric constant. Extensive simulation and experimental results are presented for a slot ring antenna with a high permittivity dielectric superstrate lens.

This paper presents emPiCASSO, a powerful electromagnetic CAD tool that provides an integrated environment for analysis, synthesis and optimization of multilayer printed antenna arrays. emPiCASSO has been built on an object-oriented foundation that allows for a systematic integration of preprocessing, processing and post-processing utilities of the CAD software. As a result, it offers a host of design-oriented features that cannot be materialized in the conventional electromagnetic CAD tools. This paper describes the various utilities and features of emPiCASSO and their theoretical foundation. Some simulation results are presented for the analysis and design of large-scale printed antenna arrays.