A very small, low-loss MMIC rat-race hybrid using elevated coplanar waveguides

A very small, low-loss monolithic microwave IC (MMIC) rat-race hybrid using elevated coplanar waveguides is proposed. A 15-GHz-band rat-race hybrid was designed and fabricated in a 0.50 mm*0.55 mm chip area. The proposed hybrid requires less than half the area used when constructing miniaturized MMIC hybrids from thin-film microstrip lines. Furthermore, coupling loss of the proposed hybrid is reduced by approximately 2 dB in comparison to that of previously reported ones.>