Duplexer requires stability in terms of fast signal switching between transmitting and receiving channels on full duplex cellular telephone equipment. In this experiment, The duplexer device is the Band Stop Filter (BSF) L-shaped method with the 7th and 9th order Butterworth response. The design begins by determining the desired frequency limit, namely 3.7 GHz. The experimental results show that the Butterworth response BSF has a better level of stability and insulation performance. In terms of order level, it has been proven that the higher order (order 9) has a better isolation performance value than the lower order (order 7).

Keywords : Duplexer, BSF, Isolation.