Ka-band Lange coupler in multilayer thick-film technology

A 3-dB Ka-band Lange coupler was implemented in a multilayer thick-film technology, which avoids the drawbacks of planar technology, e.g. bonding-wires and the limitation of the coupling level induced by the minimal resolution of the slot between the coupled lines. The coupler was realized and measured by using 50-Omega thick-film resistors as terminations. Finally, the electrical performances exhibited by the proposed coupler proved to be good with a coupling level of 4.2 dB at the central frequency, a return loss greater than 15 dB and isolation greater than 20 dB in the coupler passband.