A Symmetric Log-Periodic Balun for Ultra-Wideband Application

Compared to the conventional Log- Periodic balun, the design of a symmetric Log-Periodic balun can provide better performance over the entire designed band. A novel ultra-wideband balun with 3 to 6 GHz passband is demonstrated for Ultra-Wideband (UWB) applications. The problems of fabrication and measurement of the conventional Log-Periodic balun operated at higher frequency problems can be further improved. The magnitude and phase difference between two output ports are kept balancing at higher band edge portion. The measured amplitude imbalance is about plusmn 1.1 dB with a corresponding phase difference about plusmn 4deg. The bandwidth of the balun is around 70%.