Four tubing Duplexer using band pass and reject

A band pass duplexer for simultaneous operation of a mobile relay station is essential in the world of army communication system. A new method of designing the band pass duplexer is proposed in this paper. The main structure of the band pass duplexer is a parallel coupled line connected with a capacitor. The duplexer are designed in order to improve communication system and radio amateur. It can be implemented by attaching at the army vehicles such as land rover as repeater at operation area. It also can be used with radio amateur as a mobile repeater. The band pass duplexer works as a band pass filter which allows user to communicate with each other within a frequency range of 140 MHz to 150 MHz VHF. Therefore, the duplexer is capable to minimize loses in transmitting and receiving a signal within that frequency range.