Methods and apparatus to provide a rectangular N×M antenna element subarray block having opposed first and second major surfaces and first and second ends at opposite ends of the block, wherein the antenna elements are located at the first end of the block. A coldplate between the first inlet connector and the first outlet connector enables flow of the liquid coolant from the first inlet connector to the first outlet connector. The first inlet connector is configured to enable flow of the liquid coolant into the system in a direction that is normal to the first major surface of the block.