Light Modulation Diffusers Radiation Near-field Measurement System

This paper uses an optically modulated scatterer system to measure microwave field with minimal disturbance. This method is especially adapt to measure magnitude and phase of microwave field close to conductor and microwave field with complex path between source and field. So it can be used to measure radiation antenna's near-field and microwave into slots. The precise measurement data can be useful for antenna design and slot coupling studding. This paper gives it's deduction through reciprocity principle and the structure of the optically modulated scatterer system. An applied optically modulated scatterer system is designed and photodiodes are used as modulation module. The FFT transformation is used to transform near-fields to far-fields. An open guide axis near-field distribution is measured by this system and simulationed by HFSS, two results maintain the good consistency.