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Dispersion in periodic microstrip transmission lines was investigated by using S-parameters to calculate the characteristic impedance and the complex propagation constant. Dispersion curves determined from a variety of methods, including simulation with IE3D and measurement with a network analyzer, were compared with an analytic transcendental model providing self-consistent validation of each method. Simulated S-parameters agreed with measurement, including the case of a multi-layered substrate. Very similar dispersion curves were produced using simulated S-parameters, simulated current distributions, analytic calculation and measured S-parameters. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1010–1013, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24268 [ABSTRACT FROM AUTHOR]

Many assessments of soil C have been restricted to the <2-mm fraction, but C has recently been identified in >2-mm fractions of forest mineral soils. Our objective was to determine the importance of the >2-mm fraction to whole-soil C pools in Pacific Northwest old-growth coniferous forests. Seventy-nine pedons in 18 western Washington and Oregon forests were sampled to a depth of 100 cm. The <2-mm fraction was separated from the >2-mm fraction by airdrying, physically crushing soil, and sieving; C was determined by Leco combustion. The >2-mm fraction contained up to 46% of the whole-soil C and averaged 23% for the seven forests that had C in that fraction. Following treatment with sodium hexametaphosphate to disaggregate soil material, up to 20% of whole-soil C remained in the >2-mm fraction. Thus, the >2-mm fraction C appears to be in stable and unstable aggregates, as well as concretions. The whole-soil C in the surface 100 cm of mineral soil ranged from 30 to 400 Mg C ha-1. Multiple regression analysis indicated this C pool was positively related to available water capacity, annual precipitation, and coarse woody debris (r² = 0.63 to 0.66, n = 18 forests). Similar results were obtained with only the <2-mm soil C, which is the basis of previous regional evaluations. This suggests consideration of the >2-mm fraction does not alter our understanding of the importance of climate and soil texture as controls of soil C pools, but it does affect the quantification of soil C pools in many old-growth forests in the Pacific Northwest. [ABSTRACT FROM AUTHOR]