There is an impedance difference between cable and antenna in antenna systems. This impedance difference.,causes reflected waves. A part of the incident and the reflected waves creates a standing wave on the transmission line. To match the impedance difference at an acceptable SWR level, Balun is used. In this work, a new Broad Band Balun system has been designed. The Balun system includes four Baluns a measurement circuit and a microprocessor. The microprocessor selects the most convenient Balun for a certain frequency. The standing wave amplitude has been measured separately for each Balun using. a measurement circuit. and the convenient Balun is chosen according to measurement results. So, the designed Balun system can be used for broadband.