A compact Gysel power divider design using U-shaped and T-shaped resonators with harmonics suppression

In this paper, design process of a new compact microstrip Gysel power divider (GPD) with harmonics elimination is proposed. In the designed GPD structure, two types of resonators are applied to make transmission zeros (TZs). T-shaped resonator makes one TZ at lower frequency and U-shaped resonator makes two TZs at higher frequencies. These three created transmission zeroes by applied resonators result in the good harmonics suppressing in the Gysel divider. The LC-equivalent circuit (LCEC) of the resonators is extracted and the locations of these three transmission zeroes are calculated analytically. The proposed GPD creates three transmission zeros at near 3 GHz, 4.9 GHz, and 9.1 GHz. The proposed Gysel power divider (GPD) with applied resonators reduces the circuit size more than 66% (occupied 34% size) compared with the conventional GPD with λ/4 transmission lines. Moreover, the fractional bandwidth of the proposed divider is 50% and also suppresses up to seventh harmonic.