Dual-band in-phase filtering power dividers integrated with stub-loaded resonators

A compact microstrip dual-band in-phase filtering power divider is presented in this study. The integrated two stub-loaded resonators are applied to realise the dual-band filtering response and compact size. Based on the even-odd-mode analysis, an analytical model of the proposed power divider structure is presented. To improve the frequency selectivity, a source-load cross coupling is introduced by placing input and output coupling lines closely. A prototype of the dual-band in-phase filtering power divider centred at 3.5 and 5 GHz with 3 dB fractional bandwidth of 7.4 and 4.2% is designed, fabricated and measured. The size of the fabricated power divider is 0.27λ_g × 0.35 λ_g. The simulated and measured results are presented and show good agreement.