| 摘要 |
A coaxial cable for coupling radio frequency (RF) signals therethrough with a predetermined, nominal attenuation comprising a center conductor selected to maintain the attenuation of the coaxial cable at substantially the nominal attenuation substantially independently of the frequency of the RF signals over a predetermined frequency range, such as from 2 to 18 GHz. In a preferred embodiment of the invention, the center conductor is selected having a nominal volume resisitivity ( rho ) and a nominal permeability ( mu ), with the volume resistivity-permeability product thereof substantially varying inversely with changes in frequency of RF signals coupled through the cable. With such arrangement, a lossy coaxial cable providing substantially constant attenuation over a broad range of frequencies, such as greater than three octaves, is provided having reduced size, complexity and VSWR from conventional lossy cable assemblies comprising a conventional coaxial cable coupled in series with an attenuator. Also, the frequency response attenuation characteristics of the coaxial cable are readily and consistently reproducible, thereby providing a plurality of such cables with "conformal" loss characteristics over the operating bandwidth to facilitate interchangeability of such coaxial cables. Further, the electrical lengths of a plurality of coaxial cables may be phase-matched to a relatively tight tolerance.
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