Electrical measurements of microwave circuit board materials

This paper is intended to be helpful to those who need to frequently measure electrical properties of foil clad laminates for microwave applications. Successful and unsuccessful efforts are discussed, with emphasis on the problems of specimen preparation and laboratory technique. Various published methods for measurement of dielectric constant and dissipation of polymer based circuit board materials are briefly reviewed. Some limitations of the stripline resonator method of MIL-P-13949E are overcome by simple modifications. Quality control programs of producers and users of foil clad microwave circuit board materials require dielectric constant measurements done with precision, ease, and minimal material destruction. An empirically calibrated fixture pressed against a small area stripped of foil has been the best of several ideas tried.