Publications

Conference Papers

• V. K. Chauhan, J. Cohen, L. Xu, P. Vaughan, A. Consoli, J. Ratner, T. C. Wong, and R. Trebino, “Double-Blind Frequency-Resolved Optical Gating for Measuring Two Different Pulses Simultaneously,” inCLEO:2011 – Laser Applications to Photonic Applications, OSA Technical Digest (CD) (Optical Society of America, 2011), paper CTuO4.
  
• We demonstrate a simple method for simultaneously and robustly measuring two arbitrary, potentially very complex pulses, which we call “double-blind” FROG. It uses the standard FROG algorithm and can operate on a single shot.
  
• Trang Thai, Justin Ratner, Wenhua Chen, Tushar Thrivikraman, Gerald DeJean, Manos Tentzeris, “Impedance Characterization of Polarized Nano-material for Millimeter Wave Applications,” Accepted for presentation 2009 Antennas and Propagation Society International Symposium IEEE.
  • Polarized Nano-materials (PNM) are characterized from 26.5-40 GHz by embedding PNM multiwalled carbon nanotube (MWCNT) papers within a waveguide. A network analyzer is used to measure reflection and transmission. For the first time, carbon nanotubes are shown, experimentally, to behave as resonators.
• Justin T. Ratner, Trang Thai, Gerald R. DeJean, Manos M. Tentzeris, “Gas sensor utilizing surface plasmon resonance and carbon nanotube composite materials in the microwave regime,” Invited and accepted for presentation 2009 Applied Computational Electromagnetics Society Conference.
  • A wireless gas sensor design utilizing Carbon Nanotube composite/mixtures operating based on surface plasmon resonance is proposed and studied. The sensor, operating in the microwave frequency range, consists of a sub-wavelength rectangular aperture at its center from which the transmission of an incident wave is investigated. The sensing mechanism of this structure was shown previously to rely on a frequency shift of the enhanced transmitted signal of approximately 400 MHz at 23.5 GHz for a +2% change in epsilon_r. We investigate enhanced transmission for diff erent angles of incidence, it is shown to have good tolerance to variations (DeltaTheta = pm 5 degrees to normal) in the angle of incident microwave radiation at 23.5 GHz.
• Trang T. Thai, Amil Haque, Justin Ratner, Gerald R. DeJean, Manos M. Tentzeris, “Development of a fully-integrated ultra-sensitive wireless sensor utilizing carbon nanotubes and surface plasmon theory,” presented at IEEE Electronic Components and Technology Conference, March 2008. Motorolla Fellowship Finalist
  • A practical application of surface plasmon resonance (SPR) for the realization of an ultrasensitive, fully-integrated, fully-packaged wireless sensor, that can operate in microwave frequencies based on the gas sensitivity of carbon nanotube (CNT) mixtures, is proposed. The sensor consists of a corrugated aluminum plate whose surface is periodically covered with a thin layer of the CNT materials. The incident TM-polarized waves on this surface excite the surface plasmon (SP) mode, thus resulting in a drop of power of the reflected wave. The change in the electrical properties of the CNT mixtures when exposed to gases results in the change of the SPR observable in the reflected waves. For the first time, a CNT-based wireless sensor has been designed to show a frequency shift of 400 MHz while operating in the 60 GHz range.
• Anya Traille, Justin Ratner, Glenn D. Hopkins, Victor Tripp, “Development of a Novel Faceted, Conformal, Slotted-Waveguide Subarray for Sensor Applications with Full 360 degree Azimuth Tracking Capabilities,” IEEE Antennas and Propagation Society International Symposium June 2007, p.p. 3828-3831.
  • This paper describes the design and implementation of a conformal subarray antenna that was developed as part of a larger circular array which is intended to provide full 360 degree azimuth coverage for a sensing system operating from 16-16.6 GHz. Despite the fact that several technologies from prior art were incorporated into the design of the presented center-fed, narrow-wall slotted waveguide array, the innovative character of this approach lies in the development of a faceted conformal waveguide subarray and its use with neighboring similar arrays to provide azimuth angular tracking information. The measured reflection coefficient and radiation patterns of two fabricated prototypes demonstrate good agreement with those predicted by FEM simulations.
• Hopkins, G.D., Ratner, J., Traille, A., Tripp, V., “Aperture Efficiency of Amplitude Weighting Distributions for Array Antennas,” IEEE Aerospace Conference, March 2007.
  • Array antennas offer a wide range of opportunities in the variation of their directivity patterns through amplitude and phase control. Peak sidelobe levels may be reduced via amplitude control or weighting across the array aperture. Several authors have made significant contributions in detailing processes for synthesizing these aperture amplitude distributions for the purpose of sidelobe level control. One of the basic trade-offs when implementing amplitude weighting functions is that a trade between low sidelobe levels and a loss in main beam directivity always results. Some of the commercially available pattern calculation programs that can implement sidelobe level control do not provide calculations of the aperture efficiencies given different amplitude weightings. Calculation of the aperture efficiency can be somewhat confusing, particularly with regards to the difference between tapering via attenuation versus redistribution. The purpose of this paper is to define these terms, to provide a review of the proper normalization technique that is important in obtaining accurate aperture efficiency estimation. Descriptions of the amplitude tapers and their utility will be presented. A design example will be presented which will compare theoretical efficiencies with those obtained via finite element method simulation.