Design of a microstrip out-of-phase power divider using shorted-coupled-line transformer

This paper presents a new equal-split power divider with out-of-phase signals between two output ports. The divider comprises two transmission line sections, one resistor, one capacitor, one short stub, one shorted-coupled-line (SCL) transformer, and one quarter-wavelength (λ/4) transformer. The SCL transformer plays three crucial roles. The first and second roles are to improve selectivity of |S₂₁| and isolation of out-of-band, respectively. The third role is to produce 270° phase difference. Thus, the phase difference between SCL and λ/4 transformers can achieve 180° requirement.