LAUSR

This paper presents the practical realization of a power divider and a 90° hybrid directional coupler in an empty substrate-integrated coaxial line (ESICL) for C-band frequency applications. This new type of transmission line is very promising in terms of electric performance, bandwidth, integration with other planar circuits, and manufacturing simplicity. The ESICL has been designed for obtaining a wide monomode bandwidth with a characteristic impedance of 50 $\Omega $ . Furthermore, an improvement of the efficient transition between the ESICL and the grounded coplanar waveguide, used as feeding line, has been also proposed. The passive devices built using this technology are reduced in mass and volume, keeping robustness, and providing a well-balanced power division, as well as reduced losses and high isolation in the whole operational bandwidth. Two prototypes have been manufactured and the experimental results are in good agreement with the simulated designs.