An improvement of Wilkinson power divider with SITLs compensated microstrip bandstop filter

This paper presents a simple technique to improve the performance of Wilkinson power divider by using step-impedance transmission line (SITLs) compensated microstrip bandstop filter. The proposed power divider employs a pair of SITLs compensated bandstop filters to replace the ordinary 70.7 Ohm quarter-wavelength transmission lines. The main objective of employing the bandpass filters incorporated in the power divider structure is to suppress the spurious response at the 2^nd harmonic frequency. Simulated and measured results at 0.9 GHz operating frequency of the ordinary and the proposed Wilkinson power divider are compared. The measured results show that the insertion losses (S₂₁, S₃₁) are less than -4.2 dB while the return losses (S₁₁, S₂₂, S₃₃) are less than -18.3 dB with more than 100% fractional bandwidth. Moreover, the proposed power divider can provide more than 24.5 dB suppression at the 2^nd harmonic frequency.