Design of a planar balun

Innovation of the Marchand balun model is presented. The structure of the designed planar microstrip matching circuit is fairly simple, practical and easily fabricated without requiring complex multiple metal or dielectric layers. Moreover, the designed balun performs well. The measured phase difference between balance ports was within 180°±3° from 1.9 GHz to 3.9 GHz and results of S ₂₁ and S ₃₁ are fairly close to -3 dB from 2.4 GHz to 3.2 GHz. Design and simulation of a planar microstrip balun with its measured results show good agreement with the simulated data.