| Abstract: | In this article, an asymmetric ultra‐wideband rat‐race hybrid coupler with 180° phase shift is proposed. The primary goal of this work is to design a planar ultra‐wideband hybrid coupler with a microstrip structure by avoiding via holes and multi‐layer design. The bandwidth of an asymmetric ring hybrid is enhanced using shorted coupled lines, perturbation impedance techniques, and matching stubs. This hybrid coupler was designed and fabricated using Taconic TLX‐8 substrate with a thickness of 0.5 mm. The results of the simulation and measurement are promising and meet the desired specifications. This hybrid coupler yields a fractional bandwidth of 56% at the center frequency of 5.95 GHz based on ±1 amplitude imbalance between two output ports. |
