A sensing system for a vehicle includes a control and sensor disposed at the vehicle. The sensor includes a plurality of antennas, which includes transmitting antennas and receiving antennas. The plurality of antennas includes a two-dimensional antenna array having a rhombus grid arrangement of antennas. Outputs of the antennas are communicated to the control, and the control, responsive to the outputs of the antennas, determines the presence of one or more objects exterior the vehicle and within the field of sensing of the antennas.