In order to realize useful active phased array antennas, we have investigated the phased array behavior of a microwave coupled oscillator system which has locking sources at both ends and is controlled by the phases of the injection signals. By numerical analysis, we show that free-running frequency shift of the end oscillator of the array is effective for enlarging the scanning range of the radiated beam. An experiment on a system of waveguide type oscillators has confirmed the analytical result and rye have successfully scanned the wave radiated from an array with five active patch antennas mounted with Gunn diodes.