An antenna comprises: a first set of two subarrays and a second set of two subarrays, where each subarray comprises: a set of antenna elements; a set of shunt waveguides, where each shunt waveguide is coupled to a unique subset of antenna elements; and a series waveguide coupled to each shunt waveguide of the set of shunt waveguides; wherein all of the series waveguides are substantially parallel; wherein each subarray of the first set is interleaved with a unique subarray of the second set so as to form first interleaved subarrays and second interleaved subarrays; wherein the first interleaved subarrays and the second interleaved subarrays are adjacent; and wherein the series waveguides of the second set are disposed within the series waveguides of the first set without any interceding series waveguides.