Abstract: A phased-array antenna is provided with a dummy antenna element and a dummy transmit/receive module for testing the other transmit/receive modules by transmitting test signals to, or receiving test signals from, the other antenna elements in the array. Test signals are transmitted in a test mode that alternates with normal-mode operation. Receive power level and/or phase can be checked. The transmit/receive modules in the array are simplified in structure and improved in reliability due to the elimination of special receive check circuits. Antenna accuracy can also be improved by adjusting the phase shifters in the transmit/receive modules to compensate for variations in transmission phase.

Abstract: An MTI radar provided with a MTI processor which includes a single erasing circuit for erasing a vector signal due to a stationary target from among all the input vector signal of reflected waves both from a moving and a stationary target; and an arithmetic circuit for removing any other variations than ones from the moving target by calculating the inner product of the post-single-erasing vector signal and a pre-erasing vector signal.