Tailored and anisotropic dielectric constants through porosity in ceramic components

    Authors

    X. Gong; W. H. She; E. E. Hoppenjans; Z. N. Wing; R. G. Geyer; J. W. Halloran;W. J. Chappell

    Comments

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    Abbreviated Journal Title

    IEEE Trans. Microw. Theory Tech.

    Keywords

    anisotropy; ceramic; dielectric materials; dielectric measurements; dielectric-resonator antenna (DRA); inhomogeneous media; resonator; FABRICATION; ANTENNA; FILTERS; Engineering, Electrical & Electronic

    Abstract

    In this paper, different densities within a ceramic are used to provide a wide continuous range of dielectric constants for high-frequency applications. Cofiring different ceramic materials together to make a single unified structure to obtain different dielectric constant combinations is quite difficult due to phase stability issues and shrinkage mismatches. However, using various levels of porosity in order to alter the effective dielectric constant in the same material allows patterning different dielectric constants into a single unit. Since the structure is made from a single material, the varying porosity regions can be made compatible. Glassy-carbon-assisted and microcellular-structure-based porous titania allow for an extremely wide range of dielectric constants, ranging from 12 to 90, while maintaining a low loss tangent. Highly anisotropic materials are demonstrated herein to achieve a dielectric constant contrast of 90/9.6 using large-range aligned microcellular structure. Dielectric-resonator antennas are shown as an application of adjusting the bandwidth between 0.5% and 2.5% by tailoring the ceramic dielectric constant. A stratified-medium-loaded cavity resonator and a buried dielectric ring resonator internal to a microcellular substrate are used to demonstrate both the cofiring and variable dielectric constant capabilities of structured porosity.

    Journal Title

    Ieee Transactions on Microwave Theory and Techniques

    Volume

    53

    Issue/Number

    11

    Publication Date

    1-1-2005

    Document Type

    Article; Proceedings Paper

    Language

    English

    First Page

    3638

    Last Page

    3647

    WOS Identifier

    WOS:000233122300046

    ISSN

    0018-9480

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