Ultra-wideband power dividers with good isolation and sharp roll-off skirt

In this paper, an UWB power dividers based on single-layer microstrip topology is proposed, analyzed and designed. Following the basic idea of the design of UWB bandpass filters, quarter-wavelength short-circuited stubs are placed at the two output ports of a traditional single-stage Wilkinson divider. The expected ultra-wideband power-splitting performance can be realized with good impedance matching at the input port and 3-dB power transmission from the input to the two output ports. As a proper resistor is placed between two output ports, good isolation can be achieved in the overall UWB region. This UWB power divider has several attractive features that include, size-compactness with 0.39lambda² in area (lambda is the guided wavelength at center frequency), high in-band selectivity, sharp roll-off skirt, less number of resistors only one isolation resistor is required against several resistors and easy for fabrication on single-layer PCB technology. A prototype power divider is then designed and fabricated on the RT/Duroid 6010 substrate with a dielectric constant of 10.8, loss tangent of 0.0023 and thickness of 0.635 mm.