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This letter proposes a novel extremely low frequency (ELF) radar for localized D-region (altitude < 95 km) ionospheric anomalies that have been generated by natural geophysical processes. The proposed system would use the former U.S. Navy Wisconsin Transmitting Facility as a distant well-characterized impulsive ELF source. Sample calculations that demonstrate how passive vertical E-field detectors could characterize ionospheric conductivity depressions of variable diameter located above Los Angeles are provided. These calculations have been obtained using our recently developed three-dimensional whole-Earth electromagnetic wave propagation model based upon the rigorous finite-difference time-domain solution of Maxwell's equations. A key potential application of the proposed ELF radar system is the detection of hypothesized ionospheric earthquake precursors [ABSTRACT FROM PUBLISHER]

This letter proposes a novel extremely low frequency (ELF) radar for major oil deposits. Using our recently developed whole-Earth electromagnetic wave propagation model based upon the finite-difference time-domain method, we have determined that detection of the radial (vertical) component of the scattered H-field provides a sensitive means to detect oil fields that are located within several kilometers of the Earth's surface. As an example, we provide numerical simulations of ELF radar returns from a hypothetical Alaskan oil field excited by a 20-Hz pulse emitted from the former U.S. Navy site in Wisconsin. The proposed method would potentially provide means to rapidly and inexpensively conduct aerial surveys of thousands of square kilometers for significant oil deposits. [ABSTRACT FROM PUBLISHER]

This letter presents a scattered-field formulation for modeling dispersive media using the finite-difference time-domain (FDTD) method. Specifically, the auxiliary differential equation method is applied to Drude and Lorentz media for a scattered field FDTD model. The present technique can also be applied in a straightforward manner to Debye media. Excellent agreement is achieved between the FDTD-calculated and exact theoretical results for the reflection coefficient in half-space problems. [ABSTRACT FROM PUBLISHER]

As clock rates continue to rise, problems with signal integrity, cross-coupling, and radiation may render impractical the baseband metallic interconnects presently used in computers. A potential means to address this problem is to use bandpass wireless interconnects operating at millimeter-wave center frequencies. We have conducted experimental and finite-difference time-domain (FDTD) computational studies scaled to a 10 GHz center frequency of single-row and double-row waveguiding defects within an electromagnetic bandgap structure. Our initial experimental results scaled to 10 GHz have verified the feasibility of achieving an approximately 80% bandwidth with excellent stopband, gain flatness, and matching characteristics. When scaled to millimeter-wave center frequencies above 300 GHz, this technology appears feasible of supporting data rates in the hundreds of Gb/s. [ABSTRACT FROM PUBLISHER]