Design of a compact balun with three octant-wavelength coupled lines

A novel microwave balun with three coupled lines is provided in this paper. With broadside coupling and edge coupling among three coupled lines, the proposed balun is compact and a wide operating frequency range is obtained. At a central frequency of 2.45 GHz, this balun is fabricated on the FR4 printed circuit board and with overall size of 1.5 mm × 1.2 mm. The prototypical balun is simulated with the full-wave electromagnetic simulator IE3D. A good match between simulated and measured results validates the proposed balun.