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

Abstract

This study proposes a compact broadband 180 degrees Wilkinson divider which is composed of right-and left-handed (RH-LH) transmission lines and an additional lambda/2 transmission line to realise a 180 degrees 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 degrees Wilkinson divider are realised by means of double-sectioned structures using p-type lumped passive networks, except for the lambda/2 transmission line. The compact divider has a lumped passive realisation, even for the lambda/2 transmission line in order to further reduce the size. The measured bandwidths of the conventional 180 degrees Wilkinson divider, the conventional 1808 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 degrees 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 degrees Wilkinson divider.