Wide-band planar balun based on simplified composite right-left-handed structure

Wide-band planar microstrip balun implemented with simplified composite right/left-handed (SCRLH) structure is presented in this letter. The proposed balun consists of a wide-band Wilkinson power divider and a broadband 180 phase shifter based on SCRLH structure. The new design was simulated and validated by the measurement. In the experimental results, within the frequency range from 3.1 to 8.3 GHz (91.2%), the measured return losses of the unbalanced and balanced ports are greater than 10 dB, and the balanced ports isolation is below 15 dB. The measured amplitude and phase difference between the two balanced ports are within +/- 0.6 dB and +/- 50, respectively, over the operating frequency band.