Phased array antenna fault diagnosis based on subarray testing and cosine similarity

Phased array antenna is widely used in military field, so the fault diagnosis of phased array antenna is an important research topic. Conventional near-field and far-field pattern testing methods consider ail the radiating elements as a whole. These methods focus on how to measure the antenna pattern, and can hardly locate the antenna fault to single radiating element. To repair the phased array antenna, the fault radiating element must be located. Usually, fault locating needs to test all the radiating elements one by one. In this paper, we propose a new method to test many elements at one time. This method is based on subarray testing and cosine similarity. We divide the phased array antenna into many small subarrays, and using several test antennas in the middle-field of the antenna under test to get a set of data. These data contain the amplitudes and phases of the antenna's main lobe and side lobe. Then, using cosine similarity to compare those test data with fault data in expert database, the fault radiating elements can be located. Simulation and field test show that this method can distinguish different faults in the phased array antenna caused by different radiating elements.