A 4 /spl times/ 4 slot Butler matrix has been designed around 38 GHz band. The circuit is compact and has low losses. In the proposed design, a novel slot hybrid coupler and slot cross-over were also designed and introduced. This new configuration demonstrates the possibility to design Butler matrices using slot-line technology. Simulated results of magnitude show a good performance in terms of bandwidth (/spl sim/8 GHz). The proposed system has the advantages of low cost, small volume, light weight and ease of fabrication. The proposed Butler matrix is suitable for millimetre-wave applications.