Compact broadband 180° Wilkinson divider using right- and left-handed transmission lines

This study proposes a compact broadband 180° Wilkinson divider which is composed of rightand lefthanded (RH-LH) transmission lines and an additional λ/2 transmission line to realise a 180° phase difference. In order to reduce the circuit size while maintaining the required broad band performance, all the transmission lines with positive or negative electrical lengths in the sub-compact 180° Wilkinson divider are realised by means of double-sectioned structures using π-type lumped passive networks, except for the λ/2 transmission line. The compact divider has a lumped passive realisation, even for the λ/2 transmission line in order to further reduce the size. The measured bandwidths of the conventional 180° Wilkinson divider, the conventional 180° Wilkinson divider using LH transmission lines, the semi-compact divider and the proposed compact divider, for the given specifications of 1 dB loss, 0.5 dB magnitude difference and 10° phase imbalance between the two output ports, are 240 MHz, 840 MHz, 1.06 GHz and 950 MHz, respectively. The proposed compact divider has a 89.2% reduction in the circuit size, compared to the conventional 180° Wilkinson divider.