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BROADBAND CHARACTERIZATION METHOD FOR DIELECTRIC CONSTANT AND LOSS TANGENT

IP.com Disclosure Number: IPCOM000007180D
Original Publication Date: 1994-Jun-01
Included in the Prior Art Database: 2002-Mar-04
Document File: 2 page(s) / 98K

Publishing Venue

Motorola

Related People

Adolfo C. Reyes: AUTHOR

Abstract

The electrical properties of materials such as die- lectric constant and loss tangent are needed for the design of RF/Microwave products. The wide band of frequencies in which these products are realized requires a broadband characterization approach. Cur- rent methods used to determine the dielectric con- stant and the loss tangent are based on the resonant properties of cavities and of transmission lines. The resonant approach provides information only at the first resonant frequency and its multiples.

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MO-LA Technical Developments Volume 22 June 1994

BROADBAND CHARACTERIZATION METHOD FOR DIELECTRIC CONSTANT AND LOSS TANGENT

by Adolf0 C. Reyes

  The electrical properties of materials such as die- lectric constant and loss tangent are needed for the design of RF/Microwave products. The wide band of frequencies in which these products are realized requires a broadband characterization approach. Cur- rent methods used to determine the dielectric con- stant and the loss tangent are based on the resonant properties of cavities and of transmission lines. The resonant approach provides information only at the first resonant frequency and its multiples.

  The broadband characterization method for die- lectric constant and for loss tangent is based on first determining the propagation constant ofa reference coplanar transmission line (CPW) realized on a lossless substrate. Once the reference propagation constant is measured, the material under test is placed on top of the reference CPW or a structure of simi- lar configuration. The propagation constant of the new CPW is measured. The dielectric constant and the loss tangent ofthe material under test are calcu- lated from the measured phase and attenuation con- stants respectively.

  The first measurement provides the necessary information for obtaining the dielectric constant of the reference substrate and the losses due to the conductor. The second measurement provides infor- mation ofthe losses of the conductor plus the losses of the dielectric under test as well as the effective dielectric constant of the composite dielectric medium. Finally, the dielectric constant and the loss tangent of the material under test are obtained by applying the symmetry and the superposition prop- erties of the CPW to the...