Ultra wide-band Bezier-curve shaped directional coupler for antenna feeding networks

In this paper we present a new multilayer directional slot-coupled coupler based on Bezier curve. The proposed coupler demonstrates a wide frequency band operation between 3.1 and 10.6 GHz. Without using any matching network, a flat coupling of 3 ± 0.8 dB, return losses better than 26 dB and isolation better than 21 dB are obtained. The simulated phase difference between direct and coupled ports is 90° ± 0.6. To examine the performances of the proposed coupler simulated results are presented and discussed.