UWB planar 180° hybrid formed by in-phase and out-of-phase Wilkinson dividers

The paper describes an ultra wideband (UWB) planar 180° hybrid in microstrip-slot technology. The device uses three in-phase and one out-of-phase Wilkinson power dividers. The out-of-phase divider uses an in-phase divider with two ±90° phase shifters in the form of double microstrip to slotline transitions in its output ports. The hybrid suffers about 4dB signal loss because of the Wilkinson combiners and the microstrip-slot transitions. This shortfall is compensated by its UWB operation. The simulated and measured results of the proposed hybrid show a well-balanced power division between the output ports and good return losses of the difference (Δ) and summation (Σ) ports across the band from 3 to 11GHz. The isolation between the difference and summation ports is excellent and the phase characteristics are close to the ideal 0° and 180° across this band.