A novel compact dual-band Wilkinson power divider(PD) is researched

which consists of tri-sections impedance transformer integrated with a spiral defected ground structure(SP-DGS).To satisfy the impedance and phase conditions by using SP-DGS

the characteristics of PD such as an equal power split

impedance matching at all ports

and a good isolation between the two output ports are fulfilled at two arbitrary given frequencies simultaneously.The main advantage of this design is that the required reactance is accurately realized by SP-DGS.The design process and formulas are also given

which are strict but flexible.Finally

a 2.4 GHz/5.8 GHz dual-band PD is developed.Measured results show that the maximal passband insert-loss is 0.1dB and 0.4dB

and the return loss and isolation are both more than 15 dB in a wide frequency range.