A radio detection and ranging (RADAR) system that emits radio signals from a transmit antenna and receives reflected signals with a receive array of antenna elements. The signals received at the receive array are conveyed through a plurality of waveguide couplers. The plurality of waveguide couplers receives signals from each antenna element at a plurality of antenna ports and outputs signals from a plurality of output ports. The waveguide couplers convey signals such that the output ports receive signals from associated sub-array sets of the antenna ports. The waveguide couplers have an overlapping arrangement such that a given sub-array set of antenna ports overlaps with a neighboring sub-array set of antenna ports by including at least half of the antenna ports in the neighboring sub-array set.