Design of a 90/spl deg/ hybrid coupler with harmonic rejection characteristic

In this paper, a 90/spl deg/ hybrid coupler with the power dividing as well as harmonic rejection performance is presented. This circuit technique was realized by integrating the fundamental operation of a conventional 90/spl deg/ hybrid with a LPF characteristic. The proposed 90/spl deg/ hybrid coupler power provides not only the power dividing capability and proper phase difference but also harmonic suppression characteristic. Two types of 90/spl deg/ hybrids were successfully demonstrated by using five-pole/three-pole and five-pole/five-pole filters.