Design method of dual-band Wilkinson power divider with improved out-of-band rejection performance and high design flexibility

In this paper, a dual-band two-way equal-split Wilkinson power divider (PD) with improved out-of-band rejection and high design flexibility is proposed. The proposed structure is an originally configured impedance transformer that is composed of two impedance matching lines and a short-circuited composite right-/left handed (CRLH) transmission line (TL) stub. CRLH-TL replaces the requirement of quarter-wavelength impedance transformer and also shows the high design flexibility in proposed PDs. The characteristic impedance of composed RH-TL and LH-TL only affects the bandwidth of two pass-bands that assure high design flexibility. Whereas, π phase response in two pass-bands of short-circuited stub is attributed to the improved out-of-band rejection performance. The detailed theoretical analysis indicates the selected range of the two centre frequencies is influenced by CRLH-TL impedance matching line. The proposed dual-band PD centred at 0.90 GHz and 2.45 GHz design is theoretically calculated, simulated and fabricated. The obtained results verify that the proposed design method is having high design flexibility and good out-of-band rejection.