A Miniaturized Multilayered Marchand Balun Using Coupled Artificial Transmission Lines

A miniaturized Marchand balun is investigated in this letter. The Marchand balun is realized on a six-layered printed circuit board by integration of two coupled artificial transmission line sections. An additional artificial line is inserted in-between the coupled lines for compensating the asymmetry. With the help of the even odd mode analysis, the electrical characteristics of the coupled lines are investigated in detail. The proposed balun has the smallest occupied size among the previous designs on printed circuit boards. It features excellent amplitude and phase imbalance, and a comparable return loss bandwidth as well. The design methodology, simulation, and experimental results are introduced thoroughly in the letter.