Compact Unequal Wilkinson Power Dividers using Planar Artificial Transmission Lines

A compact planar 4 : 1 unequal Wilkinson power divider using artificial transmission lines has been designed, fabricated and experimentally verified in this paper. Instead of adopting conventional quarter-wave microstrip transmission lines, artificial transmission lines realized by a series of meandered-line inductors, parallel-plate and interdigital capacitors are employed to implement an unequal power divider of the conventional Wilkinson topology. The proposed 4 : 1 unequal power divider occupies 52.1 mm × 28.1 mm, which is about 17% of a conventional one. The measured results of the power divider are in good agreement with the simulated ones. The measurements show that such a 4 : 1 unequal Wilkinson power divider at operational frequency ranging from 0.7 GHz to 1.1 GHz has a phase imbalance less than 4 degrees and power split between 4.06 and 4.3. The impedance matching at all ports exhibits in return losses more than 12 dB, and the good isolation between the two output ports is greater than 19 dB. Moreover, another example of a 2 : 1 unequal power divider with the same topology is presented to verify the widespread applicability of such a method using artificial transmission lines.