Coupled Line 180 Hybrids With Lange Couplers

This paper presents 180° coupled line hybrids with noninterspersed inputs/outputs, which utilize Lange couplers. It demonstrates that, due to the near-TEM properties of the couplers, the asymmetry in power division found in previous work can be removed. A novel hybrid topology with increased layout flexibility and reduced substrate area is proposed and theoretically analyzed. Test circuits for the novel hybrid were designed to operate at 8 GHz and fabricated using low-temperature co-fired ceramic technology. Imperfections of the fabrication process have affected the coupled conductors of Lange couplers. A suitable simple model to account for the differences from the properties assumed in the design has been found. Samples have been measured with one port terminated in a grounded resistor, and the influence of termination was de-embedded from measured results. The de-embedded results are in good agreement with simulations.