Dual-Band Rectangular Patch Hybrid Coupler

This paper presents, for the first time, the design of a rectangular patch hybrid coupler that can operate at two arbitrary frequency bands with the same quadrature phase relation between the two outputs. The design procedure of the hybrid coupler is presented. For demonstration, a dual-band rectangular patch hybrid coupler is designed to operate in the 2.4- and 5-GHz bands corresponding to the IEEE 802.11 a/b/g bands. The measured result shows 9.3% and 18.2% bandwidth for the lower and upper frequency bands.