AbstractA dual‐band branch‐line quadrature coupler with extended bandwidth using simple three‐section branch line is presented.This proposed design exhibits larger bandwidth than existing dual‐band designs reported in previous literature. A dual‐band branch‐line coupler was designed and measured to give 34.5 and 16.4% bandwidth in the lower band and upper band, respectively, for an amplitude imbalance less than 1 dB. The achieved bandwidth is wide enough to cover wireless local area network and wideband code division multiple access applications. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 2095–2098, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25405