A Study of Microwave Measurement System Using Optically Modulated Scattering Technique

Abstract

The accuracies of the conventional electric field measurements utilizing open-ended rectangular waveguide type of probe and coaxial type of probe are affected by a feeding cable and near-by conducting objects, which are causing distortion of the measured fields. In order to minimize the perturbation of microwave fields and improve the accuracies, the scattering technique have been popularly used for the rapid microwave fields measurement. The modulated component includes the amplitude and phase information that characterizes microwave fields at the location of the scatterer. Firstly, the new architecture of the automatic measurement system is proposed for the simultaneous measurement of the amplitude and phase of microwave fields with optically modulated scatterer. The conventional system for measurement of the modulated scattering fields has an unstable measurement ability and a measurement limitation in terms of a wide band frequency range due to the imperfection of in-phase and quadrature phase operation of the coupler. The measurement results of the proposed system are compared with those of the conventional system to demonstrate the superior performance with the phase prediction result in the near and far-field range and to validate performance of the proposed system. Secondly, the new technique for simultaneous measurement of co and cross-polarized components of microwave fields is presented. This technique is based on using dual-polarized scattering probes modulated at different frequencies and aligning two linearly polarized antennas orthogonally. Finally, microwave characteristics of indium bump for flip-chip bonding are investigated for the package of the photodiode to utilize the modulated scattering technique in microwave and millimeter wave regions. Because of several advantages compared to wire bonding, flip-chip bonding technique is increasingly used instead of wire bonding.