In this paper a new technique is proposed to improve the directivity and directivity bandwidth of couplers. In this approach, a low pass filter has been inserted before isolation port. It is shown that this technique can improve coupling and coupling bandwidth. To show the performance of this approach, a coupler with small directivity bandwidth is considered. By implementing this technique on the structure, the bandwidth is increased from 0.6 GHz to 3.1 GHz.

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