This project is to study and develop high-power PIN diode switch for high-speed switching circulator. For the purpose, a variety of new approaches are tried and addressed. The developed PIN diode switch shows insertion loss of about 0.84 dB (including SMA connector loss) and isolation of more than 80 dB. And it has power handling capability of about 70 W. The fabricated PIN diode switch can be used for Wibro applications.