short talks

Saturday, November 4, 2006 - 9:30am - 10:10am
EE/CS 3-180
  • Generalized hyperbolic functions to find soliton-like solutions of

    the inhomogeneous higher-order nonlinear Schrödinger equation

    Emmanuel Yomba (University of Minnesota, Twin Cities)
    The inhomogeneous higher-order nonlinear Schrödinger (IHONLS) equation is
    studied by the use of generalized hyperbolic functions and the complex
    amplitude method. The results reveal that for the new bright soliton-type
    and dark soliton-type solutions obtained, one can control the velocity,
    the phase shift (by managing the distributed parameters of the system) and
    the shape (by choosing appropriately the two parameters introduced in the
    generalized hyperbolic functions).
  • Formulating Fano's Method as an Optimization Problem to obtain

    Broadband Tuning Limits on UWB Antennas

    Maria Cristina Villalobos (University of Texas Pan American)
    Modern broadband communications requires antennas with greatly improved
    frequency range and reduced size. It has been known since 1948 that
    there are basic physical limitations on the bandwidth that can be
    obtained for a given size antenna; however, the numerical results that
    have been available were until recently based entirely on a second-order
    model for the antenna that was (a) an approximation, and (b) only
    strictly applicable to relatively narrowband cases. In the last few
    years, a new approach based on Fano's formulation has been used which
    can apply over any bandwidth. We have reformulated Fano's method as an
    optimization problem and as a result have been able to obtain
    fundamental bandwidth limits that can in principle be calculated for any
    radiation mode. This means that one can now find the ultimate possible
    bandwidth performance for directional antennas, a result with immediate
    practical significance for designers of ultra-wideband antennas. Graphs
    of numerical limits on the in-band reflection coefficient tolerance
    versus electrical size for high-pass and band-pass tuning are presented.

    This is joint work with H.D. Foltz and J.S. McLean