Design of tri-Band quadrature hybrid coupler for WiMAX applications

As a quadrature hybrid is one important component in Butler matrix being a beamforming network for switched-beam antennas, this paper proposes a new design for quadrature hybrid coupler for WiMAX applications. To avoid the variation of different frequencies in different areas, the proposed design cover three frequency bands for WiMAX: 2.5 GHz (2.5-2.69 GHZ), 3.5 GHz (3.4-3.6 GHz) and 5.8 GHz (5.725-5.850 GHz). The proposed structure is relatively simple as it can be simply fabricated on single layer printed circuit board. The prototype is also constructed and tested to confirm its performance over the designated frequency bands.