Asymmetric Three-Port 45° Power Dividers Composed of Small-Sized Impedance Transformers

It has been demonstrated that two types of small-sized impedance transformers, constant VSWR-type transmission-line impedance transformers (CVTs) and constant conductance-type transmission-line impedance transformers (CCTs) may be utilized not only as impedance transformers but also as phase shifters. The CVTs and CCTs have arbitrary phase shifts less than 90°, which is quite different from that a conventional impedance transformer has odd multiple of 90° phase shift. Using the CCTs with 45° phase shift, asymmetric three-port 45° power dividers terminated by arbitrary impedances have been constructed and their design equations have been derived. Finally, a uniplanar asymmetric three-port 45° power divider terminated by 30¿, 60 ¿ and 50 ¿ has been fabricated on Al2O3 substrate (¿l = 9.9 and h = 635 um) in CPW´s (coplanar wave guides) and tested.