Design of a Rotman lens feed network to generate a hexagonal lattice of multiple beams

The design of a rectangular lattice with identical row and column boards of Rotman lenses to feed a hexagonal array of radiating elements is described in this paper. The resultant beams with high directivity and good isolation are arranged in a hexagonal lattice that is rotated 90° from the element lattice. A prototype network was built to excite a hexagonal array of conical horns. The measured patterns of the planar array as well as the characteristics of the individual boards agree very well with predictions.