Somayeh Khajepour - Department of Electrical Engineering, University of Shahid Beheshti, Tehran ۱۵۹۱۴, Iran
Shahrooz Asadi - Department of Electrical Engineering, University of Shahid Beheshti, Tehran ۱۵۹۱۴, Iran
Mohammad Saeid Ghaffarian - Department of Electrical Engineering, Amirkabir University of Technology, Tehran ۱۵۹۱۴, Iran
Gholamreza Moradi - Department of Electrical Engineering, Amirkabir University of Technology, Tehran ۱۵۹۱۴, Iran

This paper presents a wideband compact hybrid coupler working on 1-6 GHz frequency band. This 3-dB hybrid coupler is in slot-coupled structure designed on multilayer Rogers RO4003C substrate. The proposed coupler consists of elliptically shaped transmission line and the combination of rectangular and elliptical shaped slots on the ground plane. To improve characteristics of the designed coupler especially in lower frequency band, multisection transmission line and altering shape of the slot on ground is proposed. By etching extra rectangular slots on the ground plane the overall size reduction is achieved. Simulation results show that the proposed coupler provides coupling of 3±0.8 dB with 90°±0.85 phase shift and demonstrate the return loss and isolation better than 16 dB over 1–6 GHz (143%) frequency band which increased by 34% compared to other slot-coupled configuration in literature review. The coupler size is 20 mm × 30 mm. The results indicate that the proposed coupler covers GPS/DCS/PCS/UMTS/WiBro/ S-DMB/WiMax/WLAN frequency bands.

Hybrid; slot-coupled; wideband; multisection