Dielectric characterization using waveguide method for antenna and radome materials in space applications

This paper presents accurate, prompt, and cost-effective relative permittivity and loss tangent measurements of low-loss dielectrics such as DuPontTM VESPEL (R) SP-1 and VictrexTM polyetherketone (PEEK) 450G, which are commonly used materials in space communication antennas. It is essential for an antenna engineer to have the information regarding the electrical properties, that is, dielectric permittivity, dielectric loss tangent, magnetic permeability, and magnetic loss tangent at the frequency of interest. The test method relies on the accurate measurements of the S-parameters of the sample under test by means of Through-Reflect-Line (TRL) calibration using a Vector Network Analyzer (VNA). Nicholson-Ross-Weir (NRW) method is employed to get the conversion from S-parameters to both complex permittivity and permeability values of the samples. The experimental results are verified with the literature data of Teflon and relative permittivity and loss tangent measurements of VESPEL (R) SP-1 ( epsilon r = 3 . 119 +/- 0 . 043 ${\varepsilon }_{r}=3.119\pm 0.043$, tan delta = ( 20 . 893 +/- 4 . 042 ) * 10 - 3 $\tan \delta =(20.893\pm 4.042)* {10}<^>{-3}$) and PEEK 450G ( epsilon r = 3 . 119 +/- 0 . 015 ${\varepsilon }_{r}=3.119\pm 0.015$, tan delta = ( 5 . 654 +/- 1 . 877 ) * 10 - 3 $\tan \delta =(5.654\pm 1.877)* {10}<^>{-3}$) are presented for X-band (8-10 GHz) frequencies.