PURPOSE: To detect a target within a wide angle range as well as a distant target by shifting the phases of exciting signals supplied to vibrators of a transmitter receiver individually by receiving a phase control signal.

CONSTITUTION: Respective ROMs 1 store two values corresponding to a wide and a narrow beam width and addresses are given to said ROMs; and values corresponding to the wide or narrow beam width are selected at a time with respect to all the ROMs with a signal from an address part 5. Then preset values are loaded in respective presettable counters 2 with a load signal from a load signal generating circuit 7. The respective counters 2 begin to count in the preset states and output rectangular waves of frequency which is 1/256 time a basic clock frequency and advanced in phase by phase quantities corresponding to the preset values to respective transmitting amplifiers 3. Here, they are amplified to a prescribed transmission level and then sent out to vibrators 4-1W4-N of the transmitter receiver 4. Further, the address part 5 and circuit 7 are controlled with a signal from a control circuit 8.