Derivation of Closed‐Form Formulas for Wideband Filtering Gysel Power Divider

This study proposes a novel wideband filtering Gysel power divider with a simple structure that exhibits improved passband and stopband performances, and we derive the entire design formulas. This power divider can be easily designed using these derived equations without iterative optimization. Moreover, the stepwise design procedures are described, and the advantages are compared with those of the existing structure. The wideband Gysel power divider is designed, fabricated, and used for measurements. The measured results showed 57% in‐band fractional bandwidth, −3.89 dB insertion loss, and −13.4 dB minimum isolation. Meanwhile, the out‐band fractional bandwidth is confirmed to be 69.5%. Harmonic suppression and isolation at 2f 0 are measured to be 46 dBc and −64 dB, respectively. The selectivity was measured to be about 20 dB at a frequency 1GHz away from the higher frequency of the passband. An analysis of the measured data allows us to demonstrate the validity of our proposed structure and derived design formulas.