Design Investigation of Leaky Coaxial Cable as Coupler for Active Phased Array Calibration

摘要

Phased array antenna calibration is a technique to compensate phase and amplitude difference between the radiating elements due to its variation in T/R modules and feeding network. Different techniques and methodologies of active phased array calibration with help of embedded couplers with active/passive LRUs are developed such as coupling radiating elements, microstrip /stripline etc. These coupling measurement becomes the reference values with respect to which attenuators and phase shifters of phased arrays are adjusted during calibration. A cavity back antenna as a radiator is designed for the large phased array antenna and a leaky coaxial cable is buried within the cut of the cavity wall. Periodic lateral slots on the outer conductor of coaxial cable is introduced to leak the electromagnetic field to couple with radiating element. This leaky coaxial cable is used as a coupler for the measurement of amplitude and phase difference between the radiating elements active circuit. Measured coupling between the leaky coaxial cable and the radiating element is used as reference to adjust the amplitude and phase among the elements for phased array calibration.