Design of a filtering power divider with high selectivity based on coupled lines

In this paper, a microstrip high selectivity filtering power divider with coupling from source/load to the resonator is designed. By employing pairs of parallel‐coupled lines and asymmetrical T‐shaped resonators to construct the filtering power dividers (PD), high selectivity, and good return loss can be achieved with two transmission poles and two transmission zeros. The design procedure and analytical equations are obtained by using the even/odd‐mode analysis. The power divider operating at the central frequency of 2.1 GHz with a 3‐dB fractional bandwidth of 19% (1.9–2.4 GHz) is simulated and implemented. Good agreement between measurement and simulated results is obtained. By introducing a resistor between output ports, the isolation is better than 18.4 dB at the passband frequency, respectively. Also, the second harmonic rejection and insertion loss lower than 0.38 dB has been obtained.