Measurement of RF dielectric properties with series resonant microstrip elements

Document Type

Article

Publication Date

3-1-1998

Abstract

With the growth of the cellular telephone market and the expansion into the personal communications service (PCS) band, the need for an expanded supply of high performance, high frequency PCB materials has become critical. This article discusses using microstrip circuitry to determine the properties of a set of high performance, high frequency PCB materials. The standard stripline measurement technique, using end-coupled series resonant strips, was extended to microstrip configurations and evaluated. Microstrip transmission circuits are simpler to construct than conventional stripline techniques and can be added easily to manufactured product boards for quality control. Dielectric constants and dielectric loss tangents were determined for a number of commercial RF PCB materials. Corrections for copper conduction losses and radiative loss were evaluated and included. A comparison of the measured vs. vendor-quoted dielectric constants and loss tangents for 24 high performance RF PCB substrate materials is also presented. In an application, the losses due to dielectric absorption and the losses due to conduction losses in the traces are not separable. The distribution of actual RF energy loss between these two mechanisms is determined by frequency and circuit configuration as well as the properties of the dielectric and copper foil. Since conduction losses are a major source of loss and are dependent on the commercial material structure, characterization of conduction losses is as important in the selection of a dielectric substrate material as the properties of the dielectric.

Identifier

0032027461 (Scopus)

Publication Title

Microwave Journal

ISSN

01926225

First Page

22

Last Page

93

Issue

3

Volume

41

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