Accurate measurement method using fiber-optics for an antenna on a portable telephone

We propose an accurate measurement method for radiation and impedance characteristics of an antenna on a portable telephone. We use fiber optics for the feed instead of coaxial cables in order to remove the undesired influence of the coaxial cables. We show the proposed measurement system using the fiber optics can achieve measurement linearity as accurate as that of the conventional system using coaxial cable, and also the influence of the fiber optics is negligible. The measurement results of a monopole antenna on a rectangular box show the validity of the measurement system. On the other hand, the conventional method using the coaxial cable affects the measurement results.