Super-Compact, High-Performance Rat-Race Coupler for Sub-1 GHz 5G Applications

Two ultra-compact Rat-Race couplers are presented, which are designed using planar artificial transmission lines composed of multiple meandered sections using a novel asymmetrical T-model technique. These single and double-layer couplers are suitable for 5G sub-l GHz applications at a center frequency of 900 MHz. The miniaturized couplers occupy approximately 4.8% and 2.1 % of the area of the canonical circular coupler, respectively.