In this paper, 5.8GHz band $4{ imes}4$ Butler matrix is designed using easily accessible commercial $90^{circ}$ hybrid coupler and semirigid coaxial cable as a transmission line. This Butler matrix is very flexible to changes of antenna system specification like a frequency band because $90^{circ}$ hybrid coupler changing is all to do. The result of design is the distance of $2{ imes}2$ array antenna element is $sqrt{2}{lambda}/4$, the 4 beam directions are diagonal of array antenna and phase shifter is not necessary. The beam width is roughly $25^{circ}$ narrower because of array antenna geometry and the side lobe is about 10dB higher partially than theoretical beam pattern. But the overall beam pattern is similar with theoretical beam. This Butler matrix can be applied to switching beam antenna of 5.8GHz band Wi-Fi and WAVE system.