Array calibration and health/status check using a “reverse” transmit/receive module

A method for in situ evaluation of the health and status of individual array elements within a large phased array has been developed and demonstrated at the subarray level. The technique utilizes a special radiating element located in the center of each subarray. This center element is fed with a “reverse” T/R module that operates in the opposite sense of the regular elements in the subarray; that is, for dual-band communications arrays, it transmits at the receive frequency and receives at the transmit frequency of the other elements in the array. A similar technique can also be applied to arrays for radar. By operating in this manner, the “reverse” element can be used to self-test the regular elements in the subarray, without requiring an external RF source. This method allows for detection of element faults and failures so that error correction or repairs can be applied without significant impact to operation of the array.