Design of a UWB planar 180° hybrid exploiting microstrip-slot transitions

The article describes the design of a planar 180 hybrid with an ultra wideband (UWB) performance. The device employs two substrates with a common ground plane and various microstrip-slot transitions to achieve in-phase and out-of-phase signal division over an ultra wide frequency range. At the initial stage, simple design guidelines are used but the final dimensions are determined using a full-wave analysis and design software package. The simulated and measured results of the proposed device reveal a well balanced power split accompanied by a very good approximation of ideal 180 and 0 differential phase shift across the band 3.1 to more than 11 GHz. Also low insertion losses, good return loss at all of the four ports, high isolation between the input ports and fine isolation between output ports are noted across this frequency band. (c) 2007 Wiley Periodicals, Inc.