Short-Circuit Transmission Line Method for PIM Evaluation of Metallic Materials

In this paper, a short-circuit transmission line method is proposed for passive intermodulation (PIM) evaluation of metallic materials. The method is introduced as a current-based PIM evaluation method that is effective for characterization of metallic materials and electrical contacts. The impedance matching condition is not required for a device under test. Therefore, its shape can be advantageously chosen arbitrarily. The proposed method realizes quantitative characterization of metallic materials, and demonstrates that characterizing the materials in terms of applied current density is effective to provide a fair assessment for material choice. Using the proposed method, copper foils with arbitrary width and thickness were evaluated without any effects on characteristic impedance. The proposed method is applicable to actual microwave components such as SMA connectors. The paper presents that the PIM level obtained using the proposed method is 18 dB higher than that in the conventional impedance-matched line method. As a result, a clear interpretation from the proposed method to the matched line method is also presented.