Wireless channel data was collected in Cambridge, Massachusetts for diverse propagation environments over distances ranging from tens of meters to several kilometers using mobile 2.4-GHz transmitters and receivers. The 20-MHz bandwidth signals from eight individually movable van-top antennas were Nyquist sampled simultaneously with 12-bit accuracy. Although path-loss variance for any given link length within single residential/urban neighborhoods was large, single streets typically exhibited path-loss, L(dB) = 10 log 10 (P P) = 10 log 10 r + C, where P is the received or transmitted power, r the link-length, the street-dependent path-loss coefficient, and C the loss incurred at street intersections. Measurements yielded = 1 5+3 2 0 27 for 2 5; is the fraction of the street length having a building gap on either side. Experiments over links as short as 100 meters indicate a 10-dB advantage in estimating path loss for this model compared to optimal linear estimators based on link length alone. Measured air-to-ground links were well modeled by = 2 for the elevated LOS path, and by stochastic log-normal attenuation for the ground-level scattering environment. These models permit path-loss predictions based on readily accessible environmental parameters, and lead to efficient nodal placement strategies for full urban coverage.
This article reports a three-channel, noncontiguous, manifold multiplexer operating from 220 to 330 GHz, a 40% fractional operating bandwidth. The structure is designed and implemented using a set of ridged substrate integrated waveguides (SIWs). The ridged SIW improves the stopband bandwidth and reduces the overall structure size by 35% over a conventional SIW design. The triplexer utilizes an organic package substrate technology developed by Intel, featuring four thick copper metal layers and continuous trench vias in lieu of standard via fences, which significantly decrease the ohmic loss of the ridged SIW waveguides. Electromagnetic-circuit modeling and codesign techniques are adopted in the development of the triplexer structure. The fabricated triplexer is measured using banded millimeter-wave wafer probing and exhibits 3∼7 dB of insertion loss in the passbands and better than 10 dB of average return loss for each of the channel filters. The measured stopband attenuation is better than 27 dB for all three channels.
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