Compact wideband differential filtering power divider based on three-line coupled structure with lumped elements

A wideband differential filtering power divider using three-line coupled structure with multiple lumped elements is proposed. The equal power division ratio, filtering response, isolation and common-mode suppression are mainly derived from the symmetrical structure, three-line coupled lines with capacitors, resistors and the short lines along the vertical symmetrical line, respectively. Compared to the reported differential filtering power dividers, the proposed design shows advantages of wide bandwidth, compact size and low insertion loss (IL). A prototype with the small size of 0.5 lambda(g) x 0.08 lambda(g) (lambda(g) is the guided wavelength at the centre frequency) was designed for demonstration, which exhibits the 3 dB fractional bandwidth of 79.2% and the minimum IL of 0.48 dB.