On the Miniaturization of Microstrip Ring-Hybrid Couplers Using Gielis Supershapes

The design, development and fabrication of compact microstrip ring-hybrid couplers are presented in the present paper. In order to obtain miniaturization, lambda/4 microstrip lines in a conventional microstrip ring-hybrid are equivalently substituted with quarter-wavelength supershape transmission lines. The results show that almost 74% size reduction can be achieved as compared to a conventional ring-hybrid. For verification purpose, a sample prototype has been designed, manufactured and tested. The fabricated compact ring-hybrid coupler operates at 1.3 GHz with low amplitude and phase imbalances. The acceptable agreement between the measurement and stimulation results validates the performance of presented coupler. The proposed ring-hybrid is compact, simple, single layer, cheap and suitable for planar fabrication for utilizing in modern communication systems.