Accession Number : AD0864731

Title :   Dielectric Constant and Loss Tangent Measurement of High-Temperature Electromagnetic Window Materials.

Descriptive Note : Technical rept. 27 Mar 68-26 Jun 69,

Corporate Author : GEORGIA INST OF TECH ATLANTA ENGINEERING EXPERIMENT STATION

Personal Author(s) : Bassett, H. L. ; Bomar, S. H., Jr

Report Date : DEC 1969

Pagination or Media Count : 198

Abstract : The research performed in the development of a new technique for measuring the complex permittivity of electromagnetic window materials from ambient temperatures to 4500F is described in this report. The measurement technique employs a focused, free-space microwave bridge and a rotating disk sample heated on one side by oxy-acetylene flames. Provisions were made for eliminating flame from the microwave measurement area. Data are included to substantiate the feasibility of the measuring technique. Surface temperatures of the sample were measured by optical pyrometers, and internal temperatures were determined by embedded thermocouples. Dynamic measurements were made of the sample insertion phase and insertion loss. A transient heat conduction analysis was used to determine temperature profiles within the sample, and the electrical transmission data were correlated with the temperature profiles to give dielectric constant and loss tangent as functions of temperature. The relative dielectric constant versus temperature function of high purity slip-cast fused silica (85 percent density) is a segmented straight line. (Author)

Descriptors :   *DIELECTRIC PROPERTIES), (*REENTRY VEHICLES, RADOMES), (*RADOMES, SILICON DIOXIDE), (*SILICON DIOXIDE, MICROWAVES, TRANSPARENT PANELS, HIGH TEMPERATURE, COMPUTER PROGRAMS.

Subject Categories : Electrical and Electronic Equipment

Distribution Statement : APPROVED FOR PUBLIC RELEASE