3D-Butler matrix topologies for phased arrays

The investigation described here is being carried out within the NATALIA project funded by the ESA. This project aims at the realisation of a low-cost receive-only Ku-band phased array antenna for automotive applications for which low-cost and small dimensions are the most essential features. One possible concept for the system architecture that was evaluated in more detail was multi-beam networks employing Butler matrices arranged in a 3D fashion. Butler beams are linearly independent combinations of the array element patterns and require no active RF-phase shifting devices for pointing the antenna beam, only switches. The impact on cost and complexity on the overall design are examined using Butler matrices as a feeding network topology.