Miniature Planar Directional Coupler with Three Stubs, which is Implemented on Compact Structural Elements

This paper presents the design of a miniature planar directional coupler with three plugs connected. This coupler operates at 2 GHz center frequency and is implemented on FR4 material. Reducing the dimensions of the coupler by 70% was obtained through the use of compact structural elements. The topologies of such elements have similar characteristics with traditional lines, but at the same time they have smaller sizes. However, miniaturization was reflected in the final characteristics of the device, so the operating frequency band narrowed by 3%.