Three-Dimensional FDTD Modeling of Impulsive Electromagnetic Propagation in the Global Earth-Ionosphere Waveguide below 30 kHz

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. In fact, because clock rates approaching microwave frequencies of 20 GHz areprojected by 2010, attention is being drawn toward alternative technologies that have relativelyfavorable signal transmission characteristics. While optical interconnects could easily providethe necessary bandwidth, there are major difficulties in integrating the required GaAs lasersources into existing silicon chip technology. An alternate potential means to address thisproblem is to use bandpass wireless interconnects operating at millimeter-wave centerfrequencies. The text below reports an experimental and computational study of substrateintegrated waveguides (SIWs) optimized for use as ultrahigh-speed bandpass waveguidingdigital interconnects. The novelty of the present work resides in the successful design,fabrication, and testing of low-loss SIWs that achieve 100% relative bandwidths via optimalexcitation of the dominant TE10 mode and avoidance of the excitation of the TE20 mode. Further,it is found that these optimal structures maintain their 100% relative bandwidth while transmitting around 45° and 90° bends, and achieve measured crosstalk of better than –30 dB over the entire passband. SIWs operating at center frequencies of 50 GHz are considered here,accommodating in principle data rates of greater than 50 Gb/sec. Because existing circuit-boardtechnology permits dimensional reductions of the SIWs by yet another factor of 4:1 relative to 116the ones discussed here, bandpass operation at center frequencies approaching 200 GHz withdata rates of 200 Gb/sec are feasible. These data rates meet or exceed those expected eventuallyfor proposed silicon photonic technologies, without requiring the integration of GaAs lasersources into existing silicon chip technology. 117