A Novel Microstrip Branch-Line Coupler with Wide Suppression Band.

novel miniaturized microstrip branch-line coupler with wide suppression band is proposed in this paper. The new structure has two significant advantages, which not only effectively reduces the occupied area to 12.3% of the conventional branch-line coupler at 0.6GHz, but also has high 11th harmonic suppression performance. The measured results indicate that a bandwidth of more than 125MHz has been achieved while the phase difference between S21 and S31 is within 90◦ ± 1.0◦. The measured bandwidths of ∣S21∣ and ∣S31∣ within 3 ± 0.4 dB are 145MHz and 150 MHz, respectively. Furthermore, the measured insertion loss is comparable to that of a conventional branch-line coupler. The proposed branch-line coupler can be easily implemented by using the standard printed-circuit-board etching processes and is very useful for wireless communication systems. [ABSTRACT FROM AUTHOR]