In this paper, a novel compact ultra-wideband (UWB) power divider with triple-notched bands is investigated. Firstly, the initial UWB power divider is studied using a couple of square ring quad-mode resonators. Then, by embedding a pair of coupled triple-mode stepped impedance resonators (TMSIRs) into the initial UWB power divider, three desired notched bands are achieved. The central frequencies of the notched bands can be easily controlled by the electrical length of the TMSIRs. To validate the design theory, a novel compact UWB power divider with triple notched bands centered at frequencies of 3.7 GHz, 5.2 GHz and 7.8 GHz is designed and measured. The simulated and measured results indicate that it has a low insertion loss and good return loss performance at all the three ports and a high isolation between the two output ports across the UWB bandwidth from 3.1 to 10.6 GHz.
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