Daijiro Ishibashi

Numerical analysis of DUT-size effect on PIM measurement using Standing-Wave Coaxial Tube

In this paper evaluations of Standing-Wave Coaxial Tube Method are carried out using modified FDTD method. First, a numerical result on the miss-alignment effect is presented in comparison with an experimental result. It shows that the miss- alignment effect does not affect PIM generated. Next, an influence of the DUT size is examined using a strip conductor. An approach of a conductor to an inner of a coaxial tube influenced upon PIM. Finally, the PIM-source-size effect incorporated into a long size DUT is examined in comparison with an experimental result. It presents the period characteristic of PIM by variation of PIM-source-size.

Analysis of 3rd-order passive intermodulation generated from metallic materials

Passive Intermodulation (PIM) is caused by weak nonlinearity in a passive circuit, which has been discussed as interference in high-power microwave base-station systems. While PIM has such a negative aspect, it is applicable positively to finding defected contacts. This paper proposes a modified FDTD method involving current-mode nonlinearity. A technique to reduce the computation time using a linear calculation is also proposed. Although the study is limited to order 3 for a basic examination, validity of the proposed method is confirmed through an experiment using the open-ended coaxial method.

Influence of a foam supporter on passive intermodulation measurement using standing-wave coaxial tube method

The influences of dielectric loss due to supporting materials proximity to tested conductive materials is examined in terms of PIM characteristics. The examination is performed using the standing wave coaxial tube method, and foam with low dielectric constant is chosen as a supporting material. In this PIM-measurement method, the error due to the loss cannot be negligible especially in the calibration process to eliminate the frequency dependence of the measurement results. Therefore, a method to reduce the influence due to such loss is proposed in this paper. The proposed method employs a low-loss conductor such as silver wire, and its validity is confirmed. As a result, it is shown that the discrepancy in the calibrated process is reduced from 10dB to 1dB.

Influence of the power-consumption at non-fundamental frequency on Passive intermodulation generation

In this paper, the influence of the power-consumption at non-fundamental frequency on Passive Intermodulation generation is investigated. It is shown that nonlinear coefficients depend on the total power including the power of non-fundamental frequency, and the power-consumption at non-fundamental frequency affects PIM generation. Through a comparison of two types of PIM-sources characterized by different mechanism such as plated coaxial connectors and diodes, it is also shown that the power dependence of a3 is dominant in plated connector while the higher order PIM in multi-tone tests affects the 3rd PIM level in 2-tone tests when PIM-source is a diode-like junction.