Compact Horse Shoe Shape Rat-Race Coupler

This paper presents an unconventional design for a circular rat race coupler operating at 5 GHz frequency. The size of the novel design implemented is 21.68 mm × 15.72 mm. The unconventional design of the coupler allows 40% reduction in the size of the coupler as compared with the conventional rat race coupler without compromising on performance. Measured and simulated results of the S-parameters are provided.