Sidelobe manipulation using Butler matrix for 60 GHz physical layer secure wireless communication

With the help of the beam orthogonality characteristics associated with a Butler matrix, the concept of sidelobe manipulation is proposed. The method uses a Butler matrix parallel excited by an information data stream and artificial interference. The proposed system is implemented using a four by four Butler matrix MMIC and its secrecy performance characteristics are validated by bit error rate (BER) simulations for a 60 GHz QPSK transmission.