Electrical Characterization of Fiber-Reinforced Composites for Mast and RadomeApplications

摘要

This work was undertaken to assess the accuracy and precision achievable by usingan open-ended coaxial 'probe' in conjunction with an automated network analyzer for the characterization of the microwave dielectric properties of composites for antenna radomes. Reported herein are the influence of material thickness, surface roughness, and instrument calibration on this technique which requires only one-sided access to the material. The unknown dielectric properties of several glass fiber reinforced polymers were evaluated after the measurement system demonstrated satisfactory results on well known materials like Teflon and fused quartz. Limited low frequency testing (40 MHz) was also done on selected composites with electrodes attached for capacitance and loss measurement, yielding results in substantial agreement with those in the microwave regime. It is concluded that the microwave 'probe' technique should be applied only for materials of substantial thickness and smooth surface conditions. Because of the need for rigid fixturing, this technique is not recommended for routine applications in the field. (MM).