Microwave Field Measurement by using Semiconductor Scatterer with Optical Modulation

Microwave electric field measurement system based on the modulated scattering technique with semiconductor scatterer has been developed. The scattered wave by the scatterer was modulated with the light which has higher energy than the band-gap energy of the semiconductor. By using undoped germanium disk as the scatterer, microwave field could be detected in the frequency range of 1-7 GHz. The sensitivity was 65 dBuV/m at the frequency of 1 GHz and was increased with increasing the frequency. On near field measurements, distribution of the in-plane field component on the microstrip line and the patch antenna could be measured.