The influence of film uniformity on the performance of coaxial airline

Plated metal film of microwave devices introduced by the manufacturing process leads to a variation in the device performance. In course of testing the characters of microwave and millimeter wave devices, we often need to get the accurate electromagnetic models for film uniformity. In this paper, the influence of film uniformity on coaxial airline was studied at microwave frequencies from 200 MHz to 18 GHz. The thickness and uniformity of plated metal film of coaxial airline were measured accurately. The scattering parameters and the voltage standing wave ratio (VSWR) are dependent on the film thickness and the uniformity. Because microwave has a short wavelength, the characteristics of the reflecting and the absorbing energy of electromagnetic waves are affected by the thickness and uniformity of metal film strongly. In this paper, the transmission characteristics of an N-type coaxial airline were measured using the broadband integrative vector network analyzer (VNA). The electromagnetic characteristics of the film uniformity and the influence on coaxial airline were obtained at the same time.